grl16-031 lancaster house design proposals c & d analysis...retaining cibse tm52 summertime...

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!DD

CIBSE TM52 and Life-Cycle Cost Analysis:

Lancaster House Design Proposals C & D Analysis

Lancaster House

Orchard Street

Lincoln

LN1 1DD

Project No.: 16-031

Revision: *

Date: 07.12.16

© Richard Tibenham Consulting 2016. All Rights Reserved

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This report has been produced by:

Richard Tibenham (Director) Greenlite Energy Assessors 11 Yarborough Terrace Lincoln LN1 1HN T: 01522 581234 E: [email protected] For: Jim Palmer Quality Engineering Design Ltd St Johns Business Park Lutterworth LE17 4HB Revision Notes:

Revision: Date Notes: Assembled by:

DRAFT 06.12.16 Based on information provided by client and using suitable assumptions where necessary.

RT

* 07.12.16 Minor text changes. RT

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Contents:

1.0 Executive Summary p.4

2.0 Introduction p.5

3.0 Energy Efficiency Improvement Measures;

Models C & D p.6

4.0 Simulation Outcomes p.14

5.0 Conclusions and Recommendations p.37

Appendix A: Technical Brief on Nottingham Weather Data p.45

Appendix B: CIBSE TM52 Design Criteria p.53

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1.0 Executive Summary This report follows Greenlite Energy Assessors’ Interim Report One and Interim Report Two and further documents the thermal modelling exercise being undertaken on Lancaster House on Orchard Street, Lincoln. This report has been commissioned by Quality Engineering Design Ltd (QED), in order to estimate the energy demand, fuel demand, fuel cost and resultant C02 emissions of Lancaster House, following improvement measures. The report documents analyses into two proposed building specifications, aimed at reducing the energy demand and energy costs of the building, as specified by QED, Polkey Colkins Associates and Robert Woodheads Ltd. The two models, ‘Model C’ and ‘Model D’, account for improved HVAC, new lighting, new glazing, and either internal thermal insulation (under ‘Model C’) or external thermal insulation (under ‘Model D’). The report demonstrates that a substantial reduction in end-use energy demand can be facilitated via either option, though Model D –with external insulation, is able to offer space heating loads almost half that of Model C, as shown graphically below:

However, it is also discussed that reductions in end-use energy demand do not necessarily translate to a proportional reduction in energy costs, due to the fact that energy prices are skewed by annual fixed cost connection charges, as shown in the graph below. Particularly in the case of gas, the effect of a high connection charge is pronounced, and disincentives reductions in energy demand from a financial perspective.

The report provides further data on summertime thermal comfort metric CIBSE TM52 and provides detailed breakdowns, analyses and recommendations in the context of the energy efficiency and fuel costs of the building.

0

200,000

400,000

600,000

Model B Model C Model D

KW

h/y

r

Model Variant

Annual Energy Demand at End-use by Model (KWh/yr)

Space Heating Space Cooling Domestic Hotwater DemandLighting Auxiliary Electrical Loads Unmetered Small Power (Other)

£0.00

£5,000.00

£10,000.00

£15,000.00

£20,000.00

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Annual Fuel Cost by Model (£/yr ex.VAT)

Gas (Connection Charge) Gas (Fuel) Electricity (Connection Charge) Electricity (Fuel)

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2.0 Introduction

This third Greenlite Energy Assessors (GEA) report builds upon the modelling process already described within Interim Report One and Interim Report Two, which can be read as a preamble to this report if desired. Interim Report One focused on the behaviour of ‘Model A’, which was a theoretical building specification, accounting for the proposed floor layouts, but accounting for no further changes. This model was assessed using 2008 weather data, containing predictions of 2020 weather scenarios. Interim Report Two focused on ‘Model B’. Model B accounted for the proposed floor plans and the existing construction fabrics, as were modelled under ‘Model A’, though the simulation was run using updated 2016 weather data containing predictions of 2020 weather scenarios. Model B also accounted for improvements in the existing HVAC in order to fully satisfy CIBSE TM52 criteria, at a minimum capital expenditure. Details of the comparisons between 2008 and 2016 predictive weather data can be found in Appendix A. This report develops ‘Model B’, accounting for building specifications which not only address CIBSE TM52 criteria but also attend to minimising the energy consumption and fuel costs of the building. This has been done using two further thermal simulations –‘Model C’ and ‘Model D’, as described in Section 3 below. Disclaimer This report estimates the thermal behaviour, energy demand, fuel demand and fuel cost of Lancaster House, using detailed thermal modelling informed by site survey data. Assumptions are made within this process, which may not occur in practice (for instance the control of natural ventilation through openable windows). Whilst Greenlite take great care in assembling simulations which provide an accurate depiction of reality, certain variables, notably future energy cost trends, are difficult to predict. As such, the fuel cost data contained within this report are purely advisory. Energy costs in reality may be substantially higher or lower than those expressed. It is the responsibility of the end client to apportion adequate levels of risk to the assumptions made, in respect of where future fuel costs will lie.

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3.0 Energy Efficiency Improvement Measures; Models C & D

Two further simulations have been undertaken to establish the performance benefits of two alternative design proposals. Both options seek to reduce energy demand within the building whilst retaining CIBSE TM52 summertime thermal comfort standards. Models C & D describe variants which are the same in every way, except that ‘Model C’ accounts for an internal insulation option and ‘Model D’ accounts for an external insulation option. By virtue of these measures, air tightness and thermal bridging are also accounted to be improved proportionally. Models C and D use the same geometry as used within Model B, and described within Interim Report Two. Unless otherwise specified, parameters for Models C & D remain the same as those used within Model B. Mechanical and electrical improvements to both models otherwise are the same. The following improvements to ‘Model B’ have been made:

3.1 Model C: Model C accounts for the same parameters as ‘Model B’, with the following additions/amendments: 1. Internal Insulation Added Internal insulation has been accounted for below AND above windows, and to internal wall surfaces within occupied areas. No insulation has been applied to non-occupied areas. Insulation incorporates internally drawn rigid foam insulation, a services void, and an internal plasterboard lining, sufficient to achieve an elemental U-Value of 0.30 W/m².k. Columns between windows have been specified with 25mm of PUR rigid foam insulation faced with 13mm plasterboard internally. 2. Linear Thermal Bridging Reduced Thermal bridging around windows has received some attention, with thermal losses to window heads, sills and jambs reducing heat loss by 50% when compared to the existing building. 3. New Roof Insulation Insulation has been added to the main roof and second floor roof, incorporating the Langley TA-25 High Performance SBS modified elastomeric membrane warm roof, achieving a U-Value of 0.18 W/m².k. Note that the application of this roof build up has not been accounted for within Model C on the plant room enclosure, adjoining lean-to roof above the stairwell, and the basement area. 4. Improved Air Tightness An improved level of air infiltration has been assigned to Model C, representative of an air permeability rate of 10m³/(m².hr)@50Pa. This equates to an infiltration rate of 0.30ach at the average wind speed, as described within Table 4.16 of CIBSE Guide A (8th edition). As with Model B, the infiltration rate is assigned to fluctuate dependent upon the wind speed. This level of air tightness should be achievable through the installation of new glazing and internal insulation, where moderate attention is paid to air tightness detailing and construction.

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5. New Glazing Throughout: New Aluminium framed double glazed units have been added with characteristics similar to Saint Gobain ‘SGG Neutral Cool-Lite SKN 174 II, as detailed below: Fig 1: Proposed Glazing Specification:

Glazing Type U-Value (W/m².K)

Frame factor

g-value LT-

value Internal

Reflectance External

Reflectance Internal

Emissivity Glazing Frame Total

Office areas glazing

1.10 5.65 1.60 11% 0.41 0.69 0.7% 30.0% 3%

6. New Air Handling Units to Each Floor Four new air handling units have been specified –one for each occupied floor of the building. Air handling units are assigned to deliver up to 1,350 l/s for ground to second floors, and 1,150l/s to the third floor. Air handling units are equipped with LPHW heating coils, operating via new gas fired heating plant, and a DX cooling coil served by an integrated DX cooler, with a CoP of 3.90. Supply and extract fans to the units provide an SFP of 2.40W/l/s. Note that it is the design intention to provide cooling via the AHUs- no local cooling cassettes shall be specified. Existing ceiling mounted cassettes shall be removed. All AHUs incorporate heat recovery via variable speed thermal wheels, capable of providing up to 83.6% heat recovery. In order to maximise indoor air quality standards, and minimise energy consumption, AHUs are assigned controls based up the thermal and C02 condition of the extract air stream. Set points for these controls are assigned to provide a mixed-mode function, with night time cooling, as detailed below:

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External Air temperatures <15°C (Wintertime Mode): When the external air temperature is <15°C, ventilation shall be provided entirely via the mechanical ventilation system. During occupied time, the system shall operate at a variable volume rate, providing 50-100% of the ventilation capacity based upon thermostatic and C02 sensors located within the extract air stream. At return air temperatures <21°C, the system shall operate at 50% capacity, rising to 100% capacity as the return air temperature tends to >23°C. This helps to stabilise internal temperatures ~22°C. At return air C02 concentrations <1,000ppm, the system will operate at 50% capacity, rising to 100% capacity as the return air C02 concentration tends to >1,500ppm. These two sensor types ‘vote’ on the AHU flow rate –the higher output signal of the two governing the flow rate. The heat recovery thermal wheel is assigned to turn at the optimum speed to allow maximum heat recovery (83.6%) at return air temperatures <21°C. As return air temperatures rise, the thermal wheel begins to slow down, becoming stationary at return air temperatures >23°C. This helps stabilise internal temperatures between 21°C-23°C. When the external air temperature is <16°C, the LPHW heating coil within the AHU will heat supply air to 25°C when the supply air stream is <19°C, falling to 14°C as the supply air stream rises to ≥21°C. Regardless of the external air temperature, between the months of September-May, the LPHW heating coil will heat supply air to 24°C when the supply air stream is <17°C, falling to 22°C as the supply air stream rises to 22°C (i.e no heating). This avoids cold drafts in situations where the external weather compensation thermostat (mainly intended for radiators) is in in the ‘off’ position, but supply air temperatures after the thermal wheel are <22°C. During the period June-August, the PHW heating coil is inactive, allowing for night-time purge cooling and mechanical cooling.

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External Air temperatures >15°C (Spring & Autumn Normal Operation Mode): When the external air temperature is >15°C, ventilation shall be provided via both the mechanical ventilation system, and via natural ventilation through the opening of windows. During occupied time, the system shall operate at a variable volume rate providing 50-100% of the ventilation capacity based upon thermostatic and C02 sensors located within the extract air stream. To help regulate internal temperatures and air quality, at external temperatures >15°C it is assumed that occupants will also open openable external windows. These are assigned to be active during occupied time, and account for windows being opened progressively between internal temperatures of 22-24°C, and at C02 concentrations of 1,300-1,500ppm. This allows natural ventilation to suppress mechanical ventilation demands until the desired thermostatic or C02 set-points are achieved, thereby reducing fan loads. Critically however, if the internal temperature of the

building falls below the external air temperature, all windows are assigned to become shut. At return air temperatures <21°C, the system will operate at 50% capacity, rising to 100% capacity as the return air temperature tends to >23°C. This helps to stabilise internal temperatures ~22°C. At return air C02 concentrations <1,000ppm, the system will operate at 50% capacity, rising to 100% capacity as the return air C02 concentration tends to >1,500ppm. These two sensor types ‘vote’ on the AHU flow rate –the higher output signal of the two governing the flow rate. The heat recovery thermal wheel is assign to turn at the optimum speed to allow maximum heat recovery (83.6%) at return air temperatures <21°C. As return air temperatures rise, the thermal wheel begins to slow down, becoming stationary at return air temperatures >23°C. This helps stabilise internal temperatures between 21°C-23°C. During this phase of operation, the external air temperature is >15°C. Up to external air temperatures ≤16°C, the LPHW heating coil within the AHU will heat supply air to 25°C when the supply air stream is <19°C, falling to 14°C as the supply air stream rises to 21°C. Regardless of the external air temperature, between the months of September-May, the LPHW heating coil will heat supply air to 24°C when the supply air stream is <17°C, falling to 22°C as the supply air stream rises to 22°C (i.e no heating). This avoids cold drafts in situations where the external weather compensation thermostat (mainly intended for radiators) is in in the ‘off’ position, but supply air temperatures after the thermal wheel are <22°C.

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Internal Air Temperatures >25°C (Summertime Cooling Mode): If the external air temperature exceeds 25°C, then the ventilation and cooling system shall seek to reduce internal temperatures so as to stabilise internal temperatures ~25°C, or within the limits of CIBSE TM52. If the external air temperature is below the internal air temperature, then the system will operate in a mixed-mode, using mechanical and natural ventilation to cool the building. At internal air temperatures >25°C, a DX cooling coil shall become active to temper the supply air temperature in such a way as to provide ‘soft cooling’. Note that this is not intended to provide fully controllable internal temperatures down to 23°C. The DX cooling coil is assigned to reduce the supply air temperature to 22°C when the flow temperature after the thermal wheel is 23°C. This set point rises to provide a supply air temperature of 23°C when the flow temperature after the thermal wheel is 33°C, i.e the DX coil is capable of providing a maximum ∆T of -10°C, but only under the highest temperature scenarios. At any time however, the supply air temperature is regulated to <23°C. Likewise, if the external air temperature is below the air internal temperature, then the thermal wheel will operate under the same logic as it does in normal operation mode; The heat recovery thermal wheel is assign to turn at the optimum speed to allow maximum heat recovery (83.6%) at return air temperatures <21°C. As return air temperatures rise, the thermal wheel begins to slow down, becoming stationary at return air temperatures >23°C. This helps stabilise internal temperatures between 21°C-23°C. If the external air temperature is above the internal air temperature, then it is assumed that all windows shall become shut, and ventilation shall be provided by mechanical means only–with full heat recovery to recover ‘coolth’ from the return air stream. This method helps reduce cooling loads and the required capacity of cooling plant. A ‘traffic lights’ display may be useful in order to indicate to occupants when to control windows appropriately.

Summer Time Night Time Purge Ventilation Control: During the summer months, the system is assigned to employ a night time fabric cooling ventilation strategy. The system is assigned to provide maximum ventilation flow between the hours of 18:00-07:00 Mon-Sun when the internal air temperature is >18°C, falling to no flow at internal temperatures <17°C, AND when the external temperatures exceed the following set-points: - 18:00 >21°C - 00:00 >14°C - 06:00 >12°C - 07:00 >14°C The night time cooling function will halt if the internal air temperature falls below the external air

temperature. No heat recovery nor DX cooling is assigned during the night time cooling function.

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7. New Space Heating Plant New Remeha ‘Quinta Pro 115’ gas fired condensing boilers have been assigned to the simulations to heat wet radiator circuits and LPHW heating coils within AHUs. Both boilers provide an output of 107KW at 80/60°C flow/return temperatures. The installations account for a ‘cascade’ arrangement, whereby the secondary boiler only becomes active once the primary boiler is approaching peak capacity. Sub-zoning of radiator circuits remains similar to the existing building, with each floor essentially able to be controlled separately via floor level branch valves, and with each floor subsequently sub-zoned into a north and south zone. Within Models C & D, a third separate circuit is also present to serve the individual heating needs of the toilets and circulation areas to the west of the building and basement zones. Heating operates using the same temperature set-points as Model B, incorporating a weekday daytime set-point of 21°C and 12°C set-back temperature at all other times. A 3hr ‘pre-heat’ period is assigned from 04:00-07:00 during weekdays. Weather compensation is assigned to the radiator circulation pump(s), such that it may only become active when external temperatures are <16°C during the period September-May. Flow temperatures are also regulated using weather compensation, with 80°C flow temperatures only occurring at <0°C, and falling towards 40°C as the external air temperature tends towards 20°C. All zones remain specified with TRVs with set-points of 21°C within occupied areas and 18°C elsewhere. The ‘occupancy behaviour factor’ of +20%, used within the heating system load calculations for Model B have been reduced to 5%, owing to the use of twin pipe system and the use of better automated control equipment –offering better controllability, Distribution losses have been reduced from 5% to 2%, accounting for the inclusion of phenolic foam insulation to the circuit. Variable speed Grundfos pumps have also been accounted for, as proposed by QED. 8. New Hot Water Heating Plant Existing hot water heating plant has been replaced by 1Nr ‘Boss BUF 100-250’ dedicated hot water heating boiler and integrated storage vessel. Standing losses from this unit have been assigned at 0.0065KWh/(l.day), accounting for the use of 50mm factory applied foam insulation. Circulation losses from the secondary circulation pipework have been reduced from 16.74W/m to just 6W/m, accounting for the use of phenolic foam insulation in place of non-existent or insulation in a poor state of repair in the existing building. Variable speed Grundfos pumps have also been accounted for, as proposed by QED.

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9. New Lighting New LED lighting and new lighting controls have been accounted for on the ground to fourth floors. Lighting loads are based upon Relux plots by Whitecroft lighting for the second and third floors. Ground and first floors have been estimated based upon these figures. The basement area has remained as specified under Model B, though incurs limited lighting loads. Control of lighting has been based upon occupancy density, through the use of PIR controls, and photo-sensitive switching controls. Within the simulation, this manifests as an additional 0.9 diversity factor to account for the PIR’s, and retention of the on/off control when natural daylight illumination exceeds or falls below 400Lux. To account for the new automated controls, which replace the existing manual controls, the ‘occupancy behaviour factor’ for lighting has been reduced from 20% to 0%.

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3.2 Model D: Model D accounts for all of the improvement measures noted under Model C, with the following additions/amendments: 1. External Insulation Added External insulation has been accounted for to the entirety of the building, based upon the application of 100mm of Kingspan K5 external wall board (or similar approved product offering a thermal conductivity of ≤0.020W/m.K). No internal insulation is accounted for. The installation accounts for an external rainscreen cladding system and an internal void lined with 13mm plasterboard, to tidy up lines between structural columns and to offer a service void for radiator pipework. The elemental build-up is accounted to provide a wall U-Value of 0.17W/m².k 2. Insulation to Plant Space and Basement Roof Insulation to the same specification as the main and second floor roof (Langley TA-25 specification) is also accounted for to the plant room enclosure, lean-to roof above stairwell and basement roof within Model D. 3. All Linear Thermal Bridging Removed The application of an external insulation system accounts for all thermal bridging to be removed. This accounts for the full removal of thermal bridging at: • Window/door sills, heads and jambs. • Intermediate floor-wall functions. • Ground floor – external wall junctions. • Parapet detail/external wall/roof junction • Plant room/roof junction

! Note that linear thermal bridging can contribute substantially to heat losses. If construction junctions incur thermal bridging losses, heating loads and the required system capacities will be greater than those recorded within this simulation. Unless explicitly obvious that thermal bridges are removed, the use of 2D or 3D heat transfer modelling should be employed. 4. Improved Air Tightness An improved level of air tightness has been assigned to Model D, representative of an air permeability rate of 5m³/(m².hr)@50Pa. This equates to an infiltration rate of 0.15ach at the average wind speed, as described within Table 4.16 of CIBSE Guide A (8th edition). As with Model B, the infiltration rate is assigned to fluctuate dependent upon the wind speed. This level of air tightness should be achievable through the installation of new glazing and external insulation, where good attention is paid to air tightness detailing and construction. It would advisable to install a breathable air permeability barrier to the external side of the external insulation.

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4.0 Simulation Outcomes 4.1 Summary A detailed level of analysis has been undertaken on each simulation variant in order to ascertain a detailed understanding of the building’s behaviour in respect of energy demand, fuel costs and C02

emissions. In summary, Model C reduces the total end-use energy demand of the building by over 50%, with the vast majority of these improvements occurring as result of reduced heating loads, and to a lesser extent, via reduced lighting loads. Model D reduces the heating load assessed under Model C by a further 44%, achieving a reduction in heating load when compared to Model B of 81%. The reason for this is the improved level of thermal insulation available via the external insulation option, which is capable of reducing both elemental heat losses and those of linear thermal bridges also. The use of LED lighting and improved lighting controls indicates that lighting loads are reduced by 57%. In terms of fuel costs however, these large reductions in energy demand are not passed on as a proportional cost saving, largely as a consequence of the structure of the fuel tariff. Under Model B, the fixed connection charge for gas services of £2,339.65 amounts to 26.7% of the estimated annual gas costs (ex.VAT). Under Model D, the cost of the fixed connection charge rises to 66.3% of the total annual gas costs (ex. VAT). The structure of the tariff essentially subsidises the unit fuel cost with a heavy fixed connection fee, disincentivizing reductions in energy demand in the process. To compound the matter, whilst lighting loads are reduced substantially, the overall reduction in electrical costs is limited between Models B, C & D, since a large proportion of electrical demand is apportioned to unregulated small power loads and servers. Under Model B, electrical costs amount to 60.5% of the annual energy costs. Under Model D, this rises to 73.3% of the annual energy costs. As a consequence, Model C achieves an annual fuel cost reduction of 37.6% when compared to Model B. By comparison, although Model D achieves a reduction in heating loads of 44% when compared to Model C, the annual fuel cost reduction compared to Model B is only 40.4%; a mere 2.8% improvement over Model C. The tables and graphs below illustrate the data that has been used to draw these conclusions.

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4.2 Detailed Energy/Fuel Use/Cost & C02 Emissions Estimations Using the inputs described within this report, simulations have been conducted using both 2016 released ‘Nottingham TRY 2020’ and ‘Nottingham DSY3 2020 50th Percentile’ weather file data. The DSY3 data incurs both higher summertime temperatures and lower winter time temperatures than the TRY data, and is indicative of a ‘1 in 7 years’ high heat summer. As such, figures shown below are aggregated accounting for 6/7th TRY outputs and 1/7th DSY3 outputs. Fig 2: Estimated energy demand, fuel use and cost by end-use (Model B):

Model B

Energy End Demand Annual Energy Demand at End-use (KWh/yr)

Annual Energy Demand at Source (Fuel

demand) (KWh/yr)

Estimated Annual

Cost* (£)

Estimated C02

Emissions ((kg.C02)/yr)

Space Heating 369,184 432,277 £7,355 93,372 Basement 11,457 Ground Floor 81,947 First Floor 65,762 Existing AHU LTHW Heating Coil 39,976 New AHU LTHW Heating Coil 33,393 Second floor 59,252 Third floor 60,249 Distribution Losses 17,147

Space Cooling (includes indoor & outdoor units)

10,422 3,280 £386 1,703

Ground Floor 1,724

First Floor 2,506

New Second Floor 2,880

New Third Floor 2,179

Basement Comms Room 333

Third Floor Comms Room 801

Domestic Hot Water Demand 14,155 17,566 £1,420 3,794 Draw off at Taps 9,795 Standing Losses + Circulation Pipework losses 5,068

Lighting 65,471 64,471 £5,861 33,980 Basement 405 Ground Floor 13,866 First Floor 13,625 Second floor 21,826 Third floor 15,749

Auxiliary Electrical Loads 19,585 19,585 £1,821 10,165 LTHW Radiator Circuit Pump + DHW Primary Pump 1,390

DHW Secondary Pump 2,864 Existing AHU Supply & Extract Fan 9,905 New AHU Supply & Extract Fan 4,414 Toilet Extract Fans 1,012

Unmetered Small Power 58,808 58,808 £5,371 30,521 PC workstations, printers, copiers, fridges, kitchen kettle

51,937

Servers 6,871

Estimated Total Gas Consumption per Year 449,844 kWh

Estimated Total Gas Cost per Year £8,755 ex. VAT(inc£2,339.65 connection fee)

Estimated Total Electrical Consumption per Year 147,144 kWh

Estimated Total Electrical Cost per Year £13,439 ex. VAT(inc £483.70 connection fee)

Total Operational Energy Cost per Year £22,194 ex. VAT

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Fig 3: Estimated energy demand, fuel use and cost by end-use (Model C):

Model C Energy End Demand Annual Energy

Demand at End-use (KWh/yr)


demand) (KWh/yr)

Estimated Annual

Cost* (£)

Estimated C02


Space Heating 121,951 122,192 £2,912 26,394 Basement 7,931 Ground Floor 28,745 First Floor 17,980 GF & FF AHU LTHW Heating Coils 18,198 SF & TF AHU LTHW Heating Coils 15,130 Second floor 16,667 Third floor 14,915 Distribution Losses 2,385


4,260 1,104 £194 573

Ground Floor AHU DX coil 443 115 First Floor AHU DX coil 360 94 Second Floor AHU DX coil 353 92 Third Floor AHU DX coil 336 87 Basement Comms Room 706 182 Third Floor Comms Room 2,061 535


Lighting 28,129 28,129 £2,573 14,599 Basement 318 Ground Floor 6,461 First Floor 8,020 Second floor 7,376 Third floor 5,954

Auxiliary Electrical Loads 16,366 16,366 £1,538 8,494 LTHW Radiator Circuit Pump + DHW Primary Pump 7

DHW Secondary Pump 35 GF & FF AHU Supply & Extract Fan 7,212 SF & TF AHU Supply & Extract Fan 8,344 Toilet Extract Fans 768


50,478 50,478

Servers 6,871 6,8721

Estimated Total Gas Consumption per Yr 136,652 kWh

Estimated Total Gas Cost per Year £4,288 ex. VAT (inc £2,339.65 connection fee)

Estimated Total Electrical Consumption per Yr 102,949 kWh

Estimated Total Electrical Cost per Yr £9,548 ex. VAT (inc £483.70 connection fee)

Total Fuel Energy Cost per Yr £13,836 ex. VAT(inc connection fees)

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Fig 4: Estimated energy demand, fuel use and cost by end-use (Model D):

Model D Energy End Demand Annual Energy

Demand at End-use (KWh/yr)


demand) (KWh/yr)

Estimated Annual

Cost* (£)

Estimated C02


Space Heating 68,792 65,571 £2,152 14,871 Basement 6,437 Ground Floor 12,134 First Floor 6,726 GF & FF AHU LTHW Heating Coils 16,872 SF & TF AHU LTHW Heating Coils 14,571 Second floor 5,824 Third floor 4,866 Distribution Losses 1,362


5,207 1,283 £215 699

Ground Floor AHU DX coil 321 79 First Floor AHU DX coil 339 84 Second Floor AHU DX coil 330 82 Third Floor AHU DX coil 319 79 Basement Comms Room 1,240 304 Third Floor Comms Room 2,658 655


Lighting 28,158 28,158 £2,576 14,614 Basement 314 314 Ground Floor 6,469 6,469 First Floor 8,042 8,042 Second floor 7,385 7,385 Third floor 5,978 5,948

Auxiliary Electrical Loads 17,275 17,275 £1,618 8,966 LTHW Radiator Circuit Pump + DHW Primary Pump 3 3

DHW Secondary Pump 35 35 GF & FF AHU Supply & Extract Fan 7,640 7,640 SF & TF AHU Supply & Extract Fan 8,830 8,830 Toilet Extract Fans 768 768


50,956 46,323 £4,583

Servers 6,871 6,871 £702

Estimated Total Gas Consumption per Yr 83,422 kWh

Estimated Total Gas Cost per Year £3,529 ex. VAT (inc £2,339.65 connection fee)

Estimated Total Electrical Consumption per Yr 104,607 kWh

Estimated Total Electrical Cost per Yr £9,694 ex. VAT (inc £483.70 connection fee)

Total Fuel Energy Cost per Yr £13,223 ex. VAT(inc connection fees)

* Note that fuel costs account for the unit fuel charge, plus the fixed connection fee. Where fuel costs have been broken down by end-use, the fixed connection costs has been divided equally (not proportionally) between end-uses.

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This data shown in figures 5-8 is displayed graphically below: Fig 5: Graph showing estimated annual energy demand at end-use:

0

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h/y

r

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Annual Energy Demand at End-use by Model (KWh/yr)

Space HeatingSpace CoolingDomestic Hotwater DemandLightingAuxiliary Electrical LoadsUnmetered Small Power (Other)Unmetered Small Power (Servers)

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Fig 6: Graph showing estimated annual fuel demand:

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Annual Fuel Demand at Source by Model (KWh/yr)


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Fig 7: Graph showing estimated annual fuel cost:

£0.00

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£25,000.00


£/y

r

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Annual Fuel Cost by Model (£/yr ex.VAT)

Gas (Connection Charge)

Gas (Fuel)

Electricity (Connection Charge)

Electricity (Fuel)

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Fig 8: Graph showing estimated annual C02 emissions:

0

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(kg.C

02)/yr

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Annual C02 Emissions by Model (kg.(C02/yr))


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The graph below displays how fuel costs are estimated to accumulate up to 2035 using the ‘moderate price increase’ data described within GEA Interim Report One and Interim Report Two

(2.60% APR for gas prices and 2.62% APR for electricity prices): Fig 9: Graph showing estimated cumulative fuel costs under ‘moderate price increase’ fuel cost data:

0

100,000

200,000

300,000

400,000

500,000

600,000

2017

2018

2019

2020

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2033

2034

2035

Cumulative Fual Cost (£)

Year

Graph Showing Predicted Cumulative Energy Costs using 'Moderate Price Increase' Data for Models B, C & D

(£ ex.Vat, Corrected for Inflation)

Cumulative Total Predicted Building Energy Cost (£) (Moderate Cost Scenario)



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4.3 Winter Time Heat Loss/Heat Gain Tables Even under the improvements measures of Model D, space heating loads represent the highest end-use energy demand and highest fuel demand within the building. Therefore, controlling this parameter is of high importance. The tables shown below provide breakdowns of heat loss and heat gain for each model during the period December-March, in order to understand how the building is heated and how this heat is dissipated during the heating season. Fig 10: Model B Winter time heat loss/heat gain balance (KWh):

Model B Heat Loss/Heat Gains Balance; Based on DSY3- December to March

Heat Gains to Building Dec

(MWh) Jan

(MWh) Feb

(MWh) Mar

(MWh) TOTAL (KWh)

Radiator Heating 52.8931 45.2723 42.4164 44.1344 184,716

Heating Via Ventilation System (LPHW coils) 9.7697 7.0388 7.6398 8.0651 32,513

Heating Via Ventilation System (Supply Fans Gains)

0.5681 0.5122 0.4893 0.5618 2,131

Lighting Gains 6.5826 6.1008 5.3534 5.3292 23,366

Occupancy Gains 5.3219 4.8584 4.6281 5.3219 20,130

Equipment Gains 4.7228 4.3933 4.1388 4.7238 17,979

Solar Gains 2.5535 2.3804 3.0431 6.2513 14,228

TOTAL 82.4117 70.5562 67.7089 74.3875 295,064

Heat Losses from Building Dec

(MWh) Jan

(MWh) Feb

(MWh) Mar

(MWh) TOTAL (KWh)

Conduction: Walls -12.2633 -9.3754 -9.3734 -9.8602 -40,872

Conduction: Windows -31.2819 -25.3108 -24.6791 -27.3481 -108,620

Conduction: Rooflights -0.1022 -0.0866 -0.0928 -0.1556 -437

Conduction: Opaque Doors -0.1283 -0.0996 -0.0927 -0.1023 -423

Conduction: Roof (main & plant space) -2.7322 -2.0264 -2.0987 -2.1404 -8,998

Conduction: Roof (2nd Floor) -0.1643 -0.1306 -0.1512 -0.1766 -623

Conduction: Roof (Basement) -0.6142 -0.4558 -0.4696 -0.4930 -2,033

Conduction: Ground Floor -1.8007 -1.2275 -1.5208 -1.7098 -6,259

Conduction: Basement Floor -0.6948 -0.4669 -0.6164 -0.6303 -2,408

Conduction: Thermal Bridging -8.0783 -6.3216 -6.2235 -6.6471 -27,271

Infiltration Losses -11.7621 -16.1813 -12.3548 -13.9483 -54,247

Mechanical Ventilation Losses (Existing AHU) -5.4642 -3.9501 -4.4604 -4.5910 -18,466

Mechanical Ventilation Losses (new AHU) -4.1735 -2.9205 -3.3610 -3.3998 -13,855

Natural Ventilation Losses -3.5395 -2.5896 -2.7826 -2.9852 -11,897

A/C Cooling -0.0001 -0.0008 -0.0021 -0.0013 -4

Residual heat loss/heat gain 0.3880 0.5873 0.5701 -0.1985 1,347

TOTAL -82.4117 -70.5562 -67.7089 -74.3875 -295,064

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Fig 11: Model B Winter time heat loss/heat gain balance (% of total):

Model B: Heat Gain/Heat Loss Balance; Based on DSY3- December to March

Heat Gains to Building TOTAL

KWh % of Total

Radiator Heating 184,716 62.60%

Heating Via Ventilation System (LPHW coils) 32,513 11.02%

Heating Via Ventilation System (Supply fan gains) 2,131 0.72%

Lighting Gains 23,366 7.92%

Occupancy Gains 20,130 6.82%

Equipment Gains 17,979 6.09%

Solar Gains 14,228 4.82%

TOTAL 295,064 100.00%

Heat Losses from Building TOTAL

KWh % of Total

Conduction: Walls -40,872 13.85%

Conduction: Windows -108,620 36.81%

Conduction: Rooflights -437 0.15%

Conduction: Opaque Doors -423 0.14%

Conduction: Roof (main & plant space) -8,998 3.05%

Conduction: Roof (2nd Floor) -623 0.21%

Conduction: Roof (Basement) -2,033 0.69%

Conduction: Ground Floor -6,259 2.12%

Conduction: Basement Floor -2,408 0.82%

Conduction: Thermal Bridging -27,271 9.24%

Infiltration Losses -54,247 18.38%

Mechanical Ventilation Losses (Existing AHU) -18,466 6.26%

Mechanical Ventilation Losses (New AHU) -13,855 4.70%

Natural Ventilation Losses -11,897 4.03%

A/C Cooling -4 0.00%

Residual heat loss/heat gain 1,347 -0.46%

TOTAL -295,064 100.00%

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Fig 12: Pie chart showing Model B winter time heat gains:

Radiator Heating, 62.60%, 62%

Heating Via Ventilation System

(LPHW coils), 11.02%, 11%

Heating Via Ventilation System (Supply fan gains),

0.72%, 1%

Lighting Gains, 7.92%, 8%

Occupancy Gains, 6.82%, 7%

Equipment Gains, 6.09%, 6%

Solar Gains, 4.82%, 5%

Model B Heat Gains by Type Dec-Mar

Radiator Heating Heating Via Ventilation System (LPHW coils)

Heating Via Ventilation System (Supply fan gains) Lighting Gains

Occupancy Gains Equipment Gains

Solar Gains

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Fig 13: Pie chart showing Model B winter time heat losses:

Conduction: Walls, 13.85%, 14%

Conduction: Windows, 36.81%,

37%

Conduction: Rooflights, 0.15%,

0%

Conduction: Opaque Doors,

0.14%, 0%

Conduction: Roof (main & plant

space), 3.05%, 3%

Conduction: Roof (2nd Floor), 0.21%,

0%

Conduction: Roof (Basement), 0.69%, 1%

Conduction: Ground Floor,

2.12%, 2%

Conduction: Basement Floor,

0.82%, 1%

Conduction: Thermal Bridging,

9.24%, 9%

Infiltration Losses, 18.38%, 18%

Mechanical Ventilation Losses (Existing AHU),

6.26%, 6%

Mechanical Ventilation Losses (New AHU), 4.70%,

5%

Natural Ventilation Losses, 4.03%, 4%

A/C Cooling, 0.00%, 0%

Model B Heat Losses by Type Dec-Mar

Conduction: Walls Conduction: WindowsConduction: Rooflights Conduction: Opaque DoorsConduction: Roof (main & plant space) Conduction: Roof (2nd Floor)

Conduction: Roof (Basement) Conduction: Ground FloorConduction: Basement Floor Conduction: Thermal BridgingInfiltration Losses Mechanical Ventilation Losses (Existing AHU)Mechanical Ventilation Losses (New AHU) Natural Ventilation LossesA/C Cooling

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Fig 14: Model C Winter time heat loss/heat gain balance (KWh):

Model C Heat Loss/Heat Gains Balance; Based on DSY3- December to March

Heat Gains to Building Dec

(MWh) Jan

(MWh) Feb

(MWh) Mar

(MWh) TOTAL (KWh)




0.4764 0.4411 0.4258 0.4968 1,840

Lighting Gains 3.1794 2.9538 2.6342 2.7097 11,477

Occupancy Gains 5.0888 4.6461 4.4253 5.0888 19,249

Equipment Gains 4.6037 4.2862 4.0363 4.6062 17,532

Solar Gains 1.7249 1.7190 2.0978 4.3618 9,904

TOTAL 38.0517 33.2574 32.9355 35.9115 140,156

Heat Losses from the Building Dec

(MWh) Jan

(MWh) Feb

(MWh) Mar

(MWh) TOTAL (KWh)



Conduction: Rooflights 0.0000 0.0000 0.0000 0.0000 0




Conduction: Roof (Basement) -0.1716 -0.1099 -0.1465 -0.1526 -581



Conduction: Glazing Infill Panels -0.8361 -0.6743 -0.6547 -0.7159 -2,881

Conduction: Thermal Bridging -6.0785 -4.8345 -4.7734 -5.1562 -20,843


AHU 1 Ventilation Losses -0.5883 -0.5608 -0.5533 -0.5997 -2,302




Ductwork Losses AHU 1 -0.3388 -0.2519 -0.2694 -0.2889 -1,149

Ductwork Losses AHU 2 -0.2519 -0.2236 -0.2390 -0.1627 -877




A/C Cooling -0.0765 -0.0697 -0.0623 -0.0852 -294

Residual heat loss/heat gain -0.0548 0.5073 -0.4194 -0.5774 -544

TOTAL -38.0517 -33.2574 -32.9355 -35.9115 -140,156

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Fig 15: Model C Winter time heat loss/heat gain balance (% of total):

Model C: Heat Gain/Heat Loss Balance; Based on DSY3- December to March


KWh % of Total








TOTAL 140,156 100.00%


KWh % of Total



Conduction: Rooflights 0 0.00%




Conduction: Roof (Basement) -581 0.41%



Conduction: Glazing Infill Panels -2,881 2.06%

Conduction: Thermal Bridging -20,843 14.87%


AHU 1 Ventilation Losses -2,302 1.64%




Ductwork Losses AHU 1 -1,149 0.82%

Ductwork Losses AHU 2 -877 0.63%





Residual heat loss/heat gain -544 0.39%

TOTAL -140,156 100.00%

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Fig 16: Pie chart showing Model C winter time heat gains:

Radiator HeatingRadiator HeatingRadiator HeatingRadiator Heating, , , , 46.32%46.32%46.32%46.32%, , , , 46%46%46%46%

Heating Via Heating Via Heating Via Heating Via Ventilation System Ventilation System Ventilation System Ventilation System

(LPHW coils)(LPHW coils)(LPHW coils)(LPHW coils), , , , 10.87%10.87%10.87%10.87%, , , , 11%11%11%11%

Heating Via Heating Via Heating Via Heating Via Ventilation System Ventilation System Ventilation System Ventilation System (Supply fan gains)(Supply fan gains)(Supply fan gains)(Supply fan gains), , , ,

1.31%1.31%1.31%1.31%, , , , 1%1%1%1%

Lighting GainsLighting GainsLighting GainsLighting Gains, , , , 8.19%8.19%8.19%8.19%, , , , 8%8%8%8%

Occupancy GainsOccupancy GainsOccupancy GainsOccupancy Gains, , , , 13.73%13.73%13.73%13.73%, , , , 14%14%14%14%

Equipment GainsEquipment GainsEquipment GainsEquipment Gains, , , , 12.51%12.51%12.51%12.51%, , , , 13%13%13%13%

Solar GainsSolar GainsSolar GainsSolar Gains, , , , 7.07%7.07%7.07%7.07%, , , , 7%7%7%7%

Model C Heat Gains by Type Dec-Mar




Solar Gains

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Fig 17: Pie chart showing Model C winter time heat losses:


Conduction: Windows, 17.47%, 18%

Conduction: Opaque Doors, 0.35%, 0%

Conduction: Roof (main & plant space),

3.08%, 3%

Conduction: Roof (2nd Floor), 0.46%, 0%


Conduction: Ground Floor, 5.18%, 5%

Conduction: Basement Floor, 1.90%, 2%

Conduction: Glazing Infill Panels, 2.06%, 2%

Conduction: Thermal Bridging, 14.87%, 15%


AHU 1 Ventilation Losses, 1.64%, 2%




Ductwork Losses AHU 1, 0.82%, 1%






Model C Heat Losses by Type Dec-Mar

Conduction: Walls Conduction: WindowsConduction: Rooflights Conduction: Opaque DoorsConduction: Roof (main & plant space) Conduction: Roof (2nd Floor)Conduction: Roof (Basement) Conduction: Ground FloorConduction: Basement Floor Conduction: Glazing Infill PanelsConduction: Thermal Bridging Infiltration LossesAHU 1 Ventilation Losses AHU 2 Ventilation LossesAHU 3 Ventilation Losses AHU 4 Ventilation LossesDuctwork Losses AHU 1 Ductwork Losses AHU 2Ductwork Losses AHU 3 Ductwork Losses AHU 4Natural Ventilation Losses A/C Cooling

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Fig 18: Model D Winter time heat loss/heat gain balance (KWh):

Model D Heat Loss/Heat Gains Balance; Based on DSY3- December to March

Heat Gains (KWh) Dec

(MWh) Jan

(MWh) Feb

(MWh) Mar

(MWh) TOTAL (KWh)




0.5156 0.4926 0.4537 0.5460 2,008

Lighting Gains 3.1902 2.9636 2.6407 2.7133 11,508

Occupancy Gains 5.1468 4.6987 4.4759 5.1468 19,468

Equipment Gains 4.6442 4.3243 4.0707 4.6462 17,685

Solar Gains 1.2955 1.3189 1.6283 3.3918 7,635

TOTAL 26.8429 22.9904 24.1327 26.2401 100,206

Heat Losses (KWh) Dec

(MWh) Jan

(MWh) Feb

(MWh) Mar

(MWh) TOTAL (KWh)



Conduction: Rooflights 0.0000 0.0000 0.0000 0.0000 0




Conduction: Roof (Basement) -0.1699 -0.1115 -0.1470 -0.1487 -577



Conduction: Glazing Infill Panels -0.8361 -0.6743 -0.6547 -0.7159 -2,881

Conduction: Thermal Bridging 0.0000 0.0000 0.0000 0.0000 0











A/C Cooling -0.1415 -0.1359 -0.1142 -0.1617 -553

Residual heat loss/heat gain -0.0343 0.6859 -0.6086 -0.3387 -296

TOTAL -26.8429 -22.9904 -24.1327 -26.2401 -100,206

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Fig 19: Model D Winter time heat loss/heat gain balance (% of total):

Model D: Heat Gain/Heat Loss Balance; Based on DSY3- December to March


KWh % of Total








TOTAL 100,206 100.00%


KWh % of Total



Conduction: Rooflights 0 0.00%




Conduction: Roof (Basement) -577 0.58%



Conduction: Glazing Infill Panels -2,881 2.88%

Conduction: Thermal Bridging 0 0.00%












Residual heat loss/heat gain -296 0.30%

TOTAL -100,206 100.00%

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Fig 20: Pie chart showing Model D winter time heat gains:

Radiator Heating, 27.92%, 28%

Heating Via Ventilation System

(LPHW coils), 13.90%, 14%

Heating Via Ventilation System (Supply fan gains),

2.00%, 2%

Lighting Gains, 11.48%, 11%

Occupancy Gains, 19.43%, 19%

Equipment Gains, 17.65%, 18%

Solar Gains, 7.62%, 8%

Model D Heat Gains by Type Dec-Mar




Solar Gains

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Fig 21: Pie chart showing Model D winter time heat losses:


Conduction: Windows, 26.89%,

27%

Conduction: Opaque Doors,

0.80%, 1%

Conduction: Roof (main & plant

space), 4.34%, 4%

Conduction: Roof (2nd Floor), 0.70%,

1%


Conduction: Ground Floor, 8.05%, 8%

Conduction: Basement Floor,

2.86%, 3%

Conduction: Glazing Infill

Panels, 2.88%, 3%







Ductwork Losses AHU 2, 1.02%, 1% Ductwork Losses

AHU 3, 0.78%, 1%




Model D Heat Losses by Type Dec-Mar

Conduction: Walls Conduction: WindowsConduction: Rooflights Conduction: Opaque DoorsConduction: Roof (main & plant space) Conduction: Roof (2nd Floor)Conduction: Roof (Basement) Conduction: Ground FloorConduction: Basement Floor Conduction: Glazing Infill PanelsConduction: Thermal Bridging Infiltration LossesAHU 1 Ventilation Losses AHU 2 Ventilation LossesAHU 3 Ventilation Losses AHU 4 Ventilation LossesDuctwork Losses AHU 1 Ductwork Losses AHU 2Ductwork Losses AHU 3 Ductwork Losses AHU 4Natural Ventilation Losses A/C Cooling

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4.4 CIBSE TM52 Outcomes The simulations have been assessed against summertime thermal comfort metric CIBSE TM52 using the ‘Nottingham 2020 DSY3 50th percentile’ weather data. All areas are accounted to pass TM52, with almost all areas satisfying all three criteria, except that of Office 01_006 under Model B, which fails criterion 2 of the code. See Appendix B for a full description of TM52 design criteria. Fig 22: Table showing CIBSE TM52 compliance for Models B, C & D:

Room Name


Crite

ria 1

Crite

ria 2

Crite

ria 3

Crite

ria 1

Crite

ria 2

Crite

ria 3

Crite

ria 1

Crite

ria 2

Crite

ria 3

-01 Corridor 0 0 0 0 0 0 0 0 0

-01 High Security Access Control E 0 0 0 0 0 0 0 0 0

-01 High Security Access Control W 0 0 0 0 0 0 0 0 0

-01 Possible Dis Shower 0 0 0 0 0 0 0 0 0

-01 Shower A 0 0 0 0 0 0 0 0 0

-01 Shower B 0 0 0 0 0 0 0 0 0

-01 Shower C 0 0 0 0 0 0 0 0 0

-01 Shower D 0 0 0 0 0 0 0 0 0

-01 Showers Circulation 0 0 0 0 0 0 0 0 0

00_001 Office 0 0 0 0.3 1.6 1 0 0 0

00_002 Office 0 0 0 0 0 0 0 0 0

00_003 Office 0 0 0 0 0 0 0 0 0

00_004 Central 0 0 0 0 0 0 0 0 0

00_004 North 0 0 0 0 0 0 0 0 0

00_004 South 0 0 0 0 0 0 0 0 0

00_008 Office 0 0 0 0 0 0 0 0 0

00_009 Office 0 0 0 0 0 0 0 0 0

01 Lobby Adj Showers 0 0 0 0 0 0 0 0 0

01_001 Office 0 0 0 1 3.6 1 0 0 0

01_002 Office 0 0 0 0.8 3.2 1 0 0 0

01_003 Office 0.1 0.8 1 1 3.4 1 0 0 0

01_004 Office Central 0 0 0 0.2 1.5 1 0.1 1.3 1

01_004 Office North 0 0 0 0 0.5 1 0 0 0

01_004 Office South 0 0 0 0.6 2.3 1 0.3 1.7 1

01_004 Office South (South) 0 0 0 0.6 2.7 1 0.3 2.3 1

01_006 Office 2.5 8.2 2 0 0 0 0 0 0

01_012 Office 1 3.9 1 0 0 0 0 0 0

02_001 Office North 0 0 0 0.5 2.6 1 0.1 0.7 1

02_001 Office South East 0 0 0 0.8 3.3 1 0.2 1 1

02_001 Office South West 0 0.5 1 0.7 3.1 1 0.3 1.1 1

02_004 Office Central 0 0 0 0.1 0.8 1 0 0.2 1

02_004 Office North 0 0 0 0.1 0.7 1 0 0 0

02_004 Office South 0 0 0 0.4 2.2 1 0.2 1.5 1

02_005 Informal Meeting Space 0 0 0 0 0 0 0 0 0

02_008 Office 0 0 0 0 0 0 0 0 0

02_009 Office 0 0 0 0 0 0 0 0 0

02_010 Office 0 0 0 0 0 0 0 0 0

02_011 Office 0 0 0 0 0 0 0 0 0

03_001 Office Central 0 0 0 0.2 1.4 1 0.1 1.1 1

03_001 Office North East 0 0 0 0.1 0.8 1 0 0 0

03_001 Office North West 0 0 0 0 0 0 0 0 0

03_001 Office South 0 0 0 0.6 2.6 1 0.4 1.9 1

03_004 Informal Meeting Area 0 0 0 0 0 0 0 0 0

03_005 Meeting Room 0 0 0 0 0.5 1 0 0 0

03_006 Office 0 0 0 0 0.4 1 0 0 0

03_007 Office 0 0 0 0 0 0 0 0 0

03_008 Office 0 0 0 0.4 2 1 0 0 0

03_018 Flexible Workplace 0 0 0 0.8 3.7 1 0.5 2 1

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It should also be noted that whilst mechanical cooling is necessary to secure CIBSE TM52 compliance under Models B and C, it has been established that full CIBSE TM52 compliance is attainable under Model D without any inclusion of mechanical cooling. Whilst it would be advised to retain mechanical cooling in any case, for greater control of internal temperatures, it is not an essential requirement under the Model D specification for TM52 compliance.

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5.0 Conclusions and Recommendations 5.1 Conclusions: The outcomes of the simulation paint a more complex picture of the situation than may have been initially thought. Whilst a ‘fabric first’ approach certainly limits energy demand at end-use, the resulting cost differences between an internal and external insulation approach are skewed by the current gas tariff, which disincentives reductions in fuel use. The design team should consider what the driving factor is for improvements; energy demand, C02

emissions or fuel costs, since improvements in one field do not necessary translate to a proportional improvement in others. In terms of energy demand at end-use, space heating loads dominate the energy demands of the building. Even with the substantial improvements incorporated into Model D, space heating remains the highest end-use energy demand and the highest fuel demand within the building. As such, it is evident that attending to the space heating loads of the building is of a high priority in any energy/C02/cost reduction exercise. The winter time heat loss/heat gain balance tables and graphs provide a useful guide to understanding how the building receives and loses heat. Heat losses via moderate thermal bridging under Model C is noteworthy, incurring thermal losses almost as high as those that occur through the internally insulated walls. Whilst heat losses via glazing are significantly reduced through the double glazing specified within Models C and D, heat losses via glazing are also noteworthy, incurring 18% of total heat losses under Model C and 27% of total heat losses under Model D. Perhaps most noteworthy of all however is the effect of heat losses via infiltration. Air tightness is often something that receives scant regard under many construction projects, in part a consequence of the limited influence infiltration has within the Part L2A NCM modelling protocol. It is often the case that measures such as photovoltaic panels are used to supplement deficiencies in air tightness. In practice however, the results of the analyses demonstration the importance of heat losses via infiltration. Model C (accounting for ~10m³/(m².hr)@50pa) accounts for heat loss via infiltration being the primary mode of winter time heat loss, at 23.3% of total heat losses. Under Model D (accounting for ~5m³/(m².hr)@50pa), this falls to 18.4% of total winter time heat losses. These acknowledgements support the Passivhaus design ideology, inferring that high performance windows and high air tightness form an essential component of an energy efficient building. Heat losses through the building fabric amount to 85.5% of total losses under Model B, falling to 85.4% under Model C and to 75.3% of total losses under Model D. Remaining losses are composed of a mixture of natural ventilation and HVAC losses. Although space heating provides the highest end-use energy demand, lighting provides the highest regulated fuel use, only trumped by unregulated small power and servers within Model D (space heating retains the highest regulated fuel load within Model C). lighting loads are directly proportional to the availability of natural light, which is effected by the glazed area and glazing specification.

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5.2 Recommendations 5.2.1 Design Requirements, Pay-back Periods & Energy Tariffs Initially, the design team and end client should clarify what their goals are in terms of energy efficiency and the reasons to justify these goals. A requirement of a payback period of <5yrs has loosely been indicated to be the target under the Salix financing spreadsheet provided, though it should be noted that this is for ‘single fuel projects’. The current gas tariff provides little impetus for reductions in gas consumption, owing to the very high fixed connection fee. The structure of the energy tariffs dictate the direction of pay-back periods strongly, so this needs to form a component of the study (though lies outside the control of GEA or QED). Fuel tariffs with the lowest fixed rate charges will perform better in terms of reducing payback periods for energy saving measures. Pay-back periods for the lighting may better a 5yr limit. Remaining measures are likely to take longer than 5yrs to repay. As mentioned within Interim Report Two, a payback period <5yrs is quite short termist with regard to energy saving improvement measures. A longer term model may be worth considering. It should be remembered that, the higher the degree of absolute energy reductions achieved, the longer the pay-back period is likely to be. There will be simple measures that can be undertaken to reduce energy demands by a low-moderate proportion, which can pay for themselves in relatively short time periods. However, if a serious reduction in energy demand is required, longer pay-back periods will be incurred. 5.2.2 The Option of a Single Fuel Source With the issues covered in paragraph 5.2.1 in mind, two options are available to make pay-back periods more attractive;

a) Move to an alternative duel fuel energy tariff which incurs higher unit costs and lower fixed connection charges.

b) Move to a single fuel source –electricity, thereby removing the issue of a high fixed connection charge for gas.

The option to go fully electric would clearly be a distinct deviation away from the current HVAC specification, and may not be viable for various reasons. It would be worthy of scrutiny however. With heating loads reduced sufficiently, minimal heating could be possible via an air-to-water heat pump. Again, the governing factor in the improvement works –energy demand, C02 emissions or fuel cost reductions need to be decided to inform this decision.

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5.2.3 The Relationship Between Solar Gain and Conductive Losses Via Glazing In order for a building to be ‘passively heated’, heat gain via glazing must exceed heat losses via glazing. The graphs below show solar heat gain and conductive heat losses to the Second Floor open plan office area, split into north and south sub-zones. The graphs show that glazing to the south side of the room yields more energy as solar heat gains than it loses in conductive losses during the period March to October. The north side of the room only yields more energy as solar gains than it loses as conductive losses during the months of May to September. Obviously, these are principally not useful heat gains, since the primary heating demands lie outside of these periods. Heating loads form the largest energy demand for the building, even when thermal losses are improved under Models C & D. Heat loss via glazing is the largest mode of winter time heat loss under Model D, and the second largest under Model C. In order to achieve winter time passive solar heating, one or both of the following must be achieved;

a) Solar gains must be increased (by increasing the glazed area and/or increasing the glazing g-value.

b) Conductive thermal losses from glazing must be decreased (through the use of a reduced U-value glazing/frame specification).

More often than not, the highest heat losses from a window occur at the frame. Double glazed units can often achieve U-Values <1.10 W/(m².k). Frames however, even when thermally split, often achieve far high U-Values, in the region of 5.5 W/(m².k), as a result of their open cell construction. It may well be worth enquiring to the glazing contractor whether aluminium frames can be injected with polyurethane insulation as a means by which to reduce thermal losses at the frame. U-Values in the region of 1.0 W/(m².k) would be possible using a double glazed unit if this method was employed (and is possible). Alternatively, the use of triple glazed units should not be dismissed. As the heat loss/heat gain balance tables show, thermal losses from glazing are considerable, and the use of triple glazed units would be money well spent if looking towards longer term pay-back options. Likewise, the proposed use of glazing infill panels and Saint Gobain ‘SGG Neutral Cool-Lite SKN 174 II glazing, with a g-value of 0.4, should perhaps be reviewed. Heating and lighting loads form the two largest regulated energy demands within the building. By comparison, summertime cooling loads are much lower- just 7.5% of the heating load. As such, designing glazing for reduced summer time solar gains is possibly not the optimum route in the interests of reducing energy demand. As developed within paragraph 5.2.4 below, designing for optimised winter time heat gain and daylight illuminance, with summertime heat gains in mind, is probably a more prudent approach.

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Fig 23: Graph showing Solar Gains vs Glazing Conductive Losses (2nd Floor South)

Fig 24: Graph showing Solar Gains vs Glazing Conductive Losses (2nd Floor North)

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Heat

Gain/H

eat

Loss

(M

Wh)

Month

Solar Heat Gain vs. Glazing Conductive Losses; Second Floor Open Plan Office (South)

Conduction gain - external glazing (MWh)

Solar gain (MWh)

Solar heat gain plus glazing conductive losses (passive gains)(MWh)

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4


Heat

Gain/H

eat

Loss

(M

Wh)

Month

Solar Heat Gain vs. Glazing Conductive Losses; Second Floor Open Plan Office (North)

Conduction gain - external glazing (MWh)

Solar gain (MWh)

Solar heat gain plus glazing conductive losses (passive gains)(MWh)

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5.2.4 The Relationship Between Solar Gain and Lighting Use Solar protective glazing works by reflecting a proportion of solar irradiation, which varies dependent upon the reflective and solar absorbing properties of the glazing. As the angle of incidence tends towards zero degrees, the proportion of reflected light is increased. When orientated due south, this allows solar protective glazing to carry out its function to the best of its abilities, since during the summertime, the sun is at a high altitude, and the angle of incidence on the glass is at its lowest ( around 30°). This means that the glazing reflects the most light at the times when it is most needed– during the midday period during the summer. During the winter, when the altitude of the sun is lower, the percentage of reflected light is lesser, resulting in higher heat gains –as is desired. However, the use of solar protective glazing does incur reduced solar gains and natural light transmission, when compared the use of clear glass, during all of the year to some degree –including the times of the year when solar heat gains and natural light levels would be beneficial. Figs 25 and 26 overleaf show solar heat gains (which correlates closely to daylight illuminance) and lighting loads to the same Second Floor open plan office areas as shown in Figs 23 and 24. The graphs show that lighting loads are fairly unaffected by the levels of solar gain (and thus daylight illuminance) permitted into the room, and even when specified with daylight switching controls, lighting loads during July are not much lower than in December. This is especially noticeable on the South side of the room. The north side –subject to a higher degree of diffuse light, is lesser affected. The graphs indicate that the reduced glazed area, combined with the effect of solar protective glazing, results in illuminance levels <400lux throughout much of the year (the minimum level that would be suitable for an office environment). Lighting loads exceed cooling loads by 5.7 times, and incur costs 21 times greater. Combined with the observations noted in paragraph 5.2.3, it would be recommended to review the glazed area and/or glazing g-value to the both elevations, and investigate the impact upon space heating loads, ventilation loads, mechanical cooling loads and lighting loads. Likewise, the use of low-g glass to the north elevation serves no benefits in respect of the availability of natural light or solar gains, except that it provide a ‘balanced’ degree of solar shading to both internal elevations of the room. Whilst solar protective glazing can limit summertime heat gains, as mentioned, it can also limit wintertime solar gains and the availability of natural light, to the detriment of lighting and heating loads, which form the highest regulated energy loads within the building by a significant margin. The use of external brise-soleil in place of solar protective glass, if dimensioned appropriately, can offer a far better degree of control in terms of removing unnecessary solar gains when undesired, but also permitting a maximum quota of solar gains and daylight availability during the wintertime. It would be prudent however to incorporate internal blinds in this instance, to remove the risk of glare during high solar gain clear winter days.

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Fig 25: Graph showing Solar Gains vs Lighting Loads (2nd Floor South)

Fig 26: Graph showing Solar Gains vs Lighting Loads (2nd Floor North)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45


Solar Gains/

Lighting Load

s (M

Wh)

Month

Solar Heat Gain vs. Lighting Loads; Second Floor Open Plan Office (South)

Lighting gain (MWh) Solar gain (MWh)

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4


Solar Gains/

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s (M

Wh)

Month

Solar Heat Gain vs. Lighting Loads; Second Floor Open Plan Office (North)

Lighting gain (MWh) Solar gain (MWh)

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5.2.5 The Importance of Air Tightness The heat gain/heat loss balance tables and graphs highlight the importance of air tightness in the context of energy demand. Even when built to what is considered to be a reasonable level of air tightness (5m³/(m².hr)@50Pa under Model D), this is still the second highest mode of heat loss from the building –far more than heat loss from external walls. Building to tighter tolerances, achieving air leakage rates in the order of <1m³(m²/hr)@50pa can offer a relatively cheap method of achieving large reductions in energy demand, but it must be assigned importance if this is to be achieved. The use of an external air tightness barrier could be employed to good effect to radically reduce infiltration losses. 5.2.6 Insulating the Ground Floor As thermal losses from the building decrease through reduced conductive and infiltration losses, the relative heat loss from the as-yet uninsulated ground floor increases. Under Model D, thermal losses from the ground floor and basement floor amount to 11% of total heat losses during the period December to March. If further reductions in energy demand are pursued, there will come a point at which insulating the ground and basement floors will become a prudent measure to take. A cost analysis would be required to appreciate where this boundary lies. 5.2.7 Mechanical Extract to Toilets Natural ventilation losses during the period March to December amount to 8.9% of total heat losses. A moderate proportion of these losses occurs from open windows within toilets, which have been assigned to be open 5% of their total capacity during occupied time, in order to provide balance air for mechanical extract systems. By extending the proposed mechanical ventilation system to also serve toilets, these losses would be greatly diminished.

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5.2.8 The Role of Renewables Typically, a ‘fabric first’ approach offers the optimised route to minimum lifecycle costs over a longer term cost model and should offer optimised lifecycle costs over the lifetime of a building. However, when entering fixed rate connection charges into the mix, the balance can become skewed. It cannot be ignored that, even under Model D, electricity costs amount to £9,694 per year (ex.VAT), and a substantial proportion of this (40%), is attributed to unregulated small power loads and servers. A PV array would definitely help reduce these costs, and since the building will experience electricity generation at the same time as demand, economics in respect of feed-in-tariffs can be optimised. Likewise, the use of solar thermal water heaters could facilitate a reduction in domestic hot water heating loads, currently summing 7.6% of the buildings end-use energy demands under Model D. 5.2.9 Limits to Improvements It would be entirely feasible to operate the building with next to no heating loads, through the use of tried and tested approaches, and utilising internal heat gains and solar gains as the principal mode of heating. This could be achieved through the application of sufficient thermal insulation and air tightness measures, the appropriate control of solar gains and sufficiently efficient HVAC (in particular AHU heat exchangers). As a rectangular building with a low form factor (surface area to volume ratio), and with the long elevations of the building orientated due south and due north, the building is well orientated and formed to benefit well from passive solar heat gains. This report clearly demonstrates that substantial energy, C02 and cost savings are available via improvement measures, and it would be perfectly technically possible to continue these improvements further if so desired, to achieve performance levels akin to the Passivhaus standard. Under the current fuel tariffs however, reductions in energy demand do not necessarily translate to proportional reductions in fuel costs, therefore the data contained within this report should act as a useful guide to help determine the best route forward.

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Appendix A: Technical Brief of Nottingham Weather Data In April 2016, CIBSE released updated weather file data for all fourteen metrological data locations

across the UK.

Previously, data has been released in 2005 and in 2008.

The 2005 data contained ‘Test Reference Year’ data (TRY) and ‘Design Summer Year’ data (DSY). The

TRY files represented a typical year’s weather conditions, whilst the DSY files represented a year with

high summertime temperatures.

In 2008 weather files were released which forecast future metrological scenarios. These forecast

weather conditions in 2020, 2050 and 2080. The forecasts accounted for possible climate change

scenarios, dependent upon the impact of global C02 emissions. For each year of forecast results, a

TRY and DSY file was created, and under each file variant, ‘Low’, ‘Low-Medium’, ‘Medium-High’ and

‘High’ outlooks were produced.

In April 2016, revisions of the 2020, 2050 and 2080 outlooks were released. These have adopted

the 2008 ‘High’ outlooks, in light of the C02 emissions which have occurred. These files are a

complete re-write of the 2008 data, and now account for the following variants; TRY, DSY 1, DSY 2

and DSY 3. Under each variant, ‘10th percentile’, ‘50th percentile’ and ‘90th percentile’ sub-variants

have also been created.

These are described as follows:

TRY: Test reference year data based on data ranging 1984 -2013.

DSY 1 – Moderately warm summer. Represents a moderately warm summer year, defined as a year with a SWCDH return period closest to 7 years. DSY 2 – Short intense warm spell. Represents an intense extreme year, which is chosen as the year with the event which is about the same length as the moderate summer year (DSY 1), but has a higher intensity than the moderate summer. DSY 3 – Long, less intense warm spell. The long extreme year is determined by the year with a less intense extreme than the high intensity year (DSY 2), more intense extreme than the moderate summer year (DSY 1), but also has a longer duration than the moderate summer year.

Further reading can be found at the link below:

http://www.cibse.org/getmedia/ce7a77e8-3f98-4b97-9dbc-

7baf0062f6c6/WeatherData_TechnicalBriefingandTesting_Final.pdf.aspx

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This document briefly analyses the relationship between the new and historical file formats under

the Nottingham weather file location. The tables and graphs below describe the weather data for

the period May-September.

File

Dry-bulb temperature (°C) - % hours in range

> 20.00 > 21.00 > 22.00 > 23.00 > 24.00

Nottingham_DSY1_2020High90_.epw 8.7 6.4 4.7 3.4 2.2









Nottingham_TRY_2020High90_.epw 6.4 4.7 3.3 2.2 1.5



NottinghamDSY2020MH.fwt 11.1 7.4 4.6 3.0 1.9

NottinghamDSY05.fwt 8.0 5.0 3.2 2.0 1.0

NottinghamTRY2020ML.fwt 12.0 9.1 6.4 4.6 2.9

File

Dry-bulb temperature (°C) - % hours in range

> 25.00 > 26.00 > 27.00 > 28.00 > 29.00













NottinghamDSY2020MH.fwt 0.9 0.7 0.4 0.3 0.1

NottinghamDSY05.fwt 0.7 0.4 0.3 0.1 0.0

NottinghamTRY2020ML.fwt 2.2 1.3 0.4 0.1 0.0

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File

Dry-bulb temperature (°C) - % hours in range Peak

Temp > 30.00 > 31.00 > 32.00

Nottingham_DSY1_2020High90_.epw 0.2 0.0 0.0 31.1









Nottingham_TRY_2020High90_.epw 0.0 0.0 0.0 30.0



NottinghamDSY2020MH.fwt 0.0 0.0 0.0 30.2

NottinghamDSY05.fwt 0.0 0.0 0.0 29.1

NottinghamTRY2020ML.fwt 0.0 0.0 0.0 28.4

Comments:

• All 2016 DSY weather data is of a higher temperature than the 2008 DSY ‘Medium-High’ and

2005 DSY data.

• The 2016 DSY 1 data contains the ‘most favourable’ data in terms of designing for

summertime internal temperatures.

• The 2016 DSY 2 data contains a higher frequency of temperatures in the range 20-32°C

than that of DSY 1, most significantly towards the lower end of the temperature range, with

temperatures >20°C ~2% more frequent, and temperatures >30°C only ~0.1% more

frequent.

• The 2016 DSY 2 data contains the highest recorded temperatures, some 3°C higher than

either 2016 DSY 1 or DSY 3.

• The 2016 DSY 3 data contains significantly higher frequencies of temperatures in the range

20-29°C.

• The 2016 DSY 3 data contains marginally lower peak temperatures than the 2016 DSY 1

data.

• There is limited variation between 10th, 50th or 90th percentile data for each 2016 data set.

In terms of TM52 compliance, if utilising 2016 data, the DSY 1 data would be the most lenient,

though still more demanding than DSY 2005 or DSY 2008 ‘Medium-High’ data.

The 2016 DSY 2 data would represent the most demanding conditions by which to demonstrate

Criterion 2 and Criterion 3 compliance (daily weighted exceedance upper limit temperature).

The 2016 DSY 3 data would represent the most demanding conditions by which to demonstrate

Criterion 1 and Criterion 2 compliance (hours of exceedance and daily weighted exceedance).

Assessing under both 2016 DSY 2 and DSY 3 would represent the most demanding combination of

conditions. The use of the ‘10th percentile’ data would be the most demanding, but only by an

almost negligible margin when compared to the 50th and 90th percentile predictions.

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Graph showing;

- 2005 Nottingham DSY (Green)

- 2008 Future 2020 DSY ‘Medium High’ (Blue)

- 2016 Future 2020 DSY 1 ‘90th percentile’ (Red)

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Graph showing;




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Graph showing;

- 2016 Future 2020 DSY 3 ‘90th percentile’ (Red; lower temperatures)

- 2016 Future 2020 DSY 3 ‘50th percentile’ (Blue; medium temperatures)

- 2016 Future 2020 DSY 3 ‘10th percentile’ (Green; high temperatures)

00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 00:00

28

26

24

22

20

18

16

14

12

Te

mp

era

ture

(°C

)

Date: Wed 18/Aug

Dry-bulb temperature: (Nottingham_DSY3_2020High90_.epw) Dry-bulb temperature: (Nottingham_DSY3_2020High50_.epw)

Dry-bulb temperature: (Nottingham_DSY3_2020High10_.epw)

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Graph showing;

- 2008 Future 2020 TRY ‘Medium Low’ (Blue)

- 2016 Future 2020 TRY ‘90th percentile’ (Red)

May Jun Jul Aug Sep Oct

30

28

26

24

22

20

18

16

14

12

10

8

6

4

2

Te

mp

era

ture

(°C

)

Date: Tue 01/May to Sun 30/Sep

Dry-bulb temperature: (NottinghamTRY2020ML.fwt) Dry-bulb temperature: (Nottingham_TRY_2020High90_.epw)

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Appendix B: CIBSE TM52 Design Criteria

CIBSE TM52 is the most up to date definition of overheating within buildings that the Chartered Institute of Building Services Engineers (CIBSE) have defined. The code now forms part of the latest revision of CIBSE Design Guide A. The code defines a room as being subject to overheating where it fails two or more of the definitions below. The guide does however not specifically specify which weather files are appropriate, except for indicating that the use of a DSY type weather is necessary. Therefore, it is the task of the design team to agree upon a suitable weather file for testing.

Criterion 1: Hours of Exceedence The first criterion sets a limit for the number of hours that the operative temperature can exceed the threshold comfort temperature (upper limit of the range of comfort temperature) by 1°K or more during the occupied hours of a typical non—heating season (1 May to 30 September). This criterion is assessed as follows:This criterion is assessed as follows:This criterion is assessed as follows:This criterion is assessed as follows: The number of hours (He) during which ∆T is greater than or equal to one degree (K)

during the period May to September inclusive shall not be more than 3 per cent of

occupied hours.

Where:

∆T = TOP - TMAX

Where:

TOP = Actual operative temp in a given room

TMAX = The limiting maximum acceptable temperature

Where:

TMAX = 0.33TRM + 21.8

Where:

TRM =the running mean of the outdoor air temperature

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Criterion 2: Daily weighted Exceedance

The second criterion deals with the severity of overheating within any one day, which can

be as important as its frequency, the level of which is a function of both temperature rise

and its duration. This criterion sets a daily limit for acceptability.

To allow for the severity of overheating the weighted exceedance (WE) shall be less than

or equal to 6 in any one day where:

WE = (∑hE) x WF

= (he0 x 0) + (he1 x 1) + (he2 x 2) + (he3 x 3)

Where the weighted factor WF = 0 if ∆T ≤ 0, otherwise WF = ∆T, and hey is the time (h)

when WF = y.

Criterion 3: Upper limit Temperature

The third criterion sets an absolute maximum daily temperature for a room, beyond which

the level of overheating is unacceptable.

To set an absolute maximum value for the indoor operative temperature the value of ∆T

shall not exceed 4°K.

grl16-031 lancaster house design proposals c & d analysis...retaining cibse tm52 summertime...

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