sustainable design statement for warwickshire county council

Issue Number 02

09.05.2019

Sustainable Design Statement

for

High Meadow Infant School

Warwickshire County Council


JHE/AJM/VSS/180960/17- 2/R001 - Issue Number 02

Document History Issue Date Comment Author Chk’d

01 25.03.2019 Planning Submission VSS AJM 02 09.05.2019 Minor Update(s) SMA PJV


JHE/AJM/VSS/180960/17- 2/R001 - Issue Number 02

Contents

1.0 Executive Summary .......................................................................................... 1

2.0 Introduction ....................................................................................................... 2

3.0 Approach ........................................................................................................... 2

4.0 Passive Sustainable Design ............................................................................... 3 Thermal Performance 3 4.1 Solar Performance 3 4.2 Thermal Mass Activation 3 4.3 Space Conditioning Strategy 3 4.4 Passive Design Solution 3 4.5

5.0 Dynamic Thermal Modelling ............................................................................ 4 Introduction 4 5.1 HVAC System Efficiencies 4 5.2 Electrical Services 5 5.3 Part L 2013 Compliance 5 5.4

6.0 Low and Zero Carbon Technologies ................................................................ 6 Building Energy Demand and Low Carbon Technology Contribution 7 6.1 Low and Zero Carbon Technologies 7 6.2 Considering Noise and Land Use 8 6.3 Project Specific Technical Assessment Factors 9 6.4 Financial Analysis and Payback 10 6.5

7.0 Conclusions ...................................................................................................... 12

Appendix A Renewable Energy Options

Appendix B BRUKL Report


1 JHE/AJM/VSS/180960/17- 2/R001 - Issue Number 02

1.0 Executive Summary Pick Everard were commissioned to provide dynamic thermal simulation and sustainable design recommendations for the new-built Teaching block of High Meadow Infant School. A two stage analysis was conducted in order to assess what technologies were appropriate for the site and then to assess the financial and technical viability of installation of those technologies. As there is limited natural gas to the site, the primary heating strategy for the building is via Air Source Heat Pumps (ASHP). This feasibility study demonstrates that the use of ASHPs helps to achieve the 10% renewable energy contribution set as a planning requirement by North Warwickshire Borough Council for all major developments. Photovoltaics were also found to offer a feasible solution, but will not be taken forward as part of the scheme due to the requirements of the Building Regulations being fully satisfied by the proposed ASHP installation. These are initial results at the planning stage and may change as the design develops.

Energy Consumption

(MWh) Carbon Emissions

(tCO2)


12.4 17.3

Part L 2013 Compliant

14.3 18.2

Part L 2013 with ASHP Installation

Target Emissions Rate (kgCO2/m2) 17.3

Building Emissions Rate (kgCO2/m2) 18.2

Improvement over Part L2A 2013 5.2%



2.0 Introduction Pick Everard were commissioned to provide dynamic thermal simulation and to consider in relative terms the initial feasibility of low carbon energy technologies for the proposed new teaching block of High Meadow Infant School. The purpose of this report is to support of the planning application and also to provide the compliance/assessment evidence at the current design stage for: • Part L2A

• Local Planning policy

The project should comply with the sustainability requirements of at least 10% energy generation from renewable energy in new developments of North Warwickshire Borough Council. The following early stage passive design analysis and renewable energy feasibility study has informed the design development of the building.

3.0 Approach The following three stage process will be followed by the design team.

The purpose of this report is to provide a detailed account of how this hierarchical process has been followed at the concept design stage and how it has informed the design of an energy efficient and low carbon design solution.



4.0 Passive Sustainable Design

Thermal Performance 4.1

The table below demonstrates the three standards of fabric performance which were considered at this design process for the High Meadow Infant School, the ‘Best Practice’ U-values will be used where possible.

CONSTRUCTION DESIGN OPTIONS - Building U-values (W/m2.K)

Minimum Standard Notional Building Best Practice

External Wall 0.35 0.26 0.22 Ground Floor 0.25 0.22 0.18 Roof 0.25 0.18 0.14 External Glazing 2.20 1.6 1.8

The air permeability was targeted at 5 m3/m2.h @ 50 Pa.

Solar Performance 4.2

The glazing has been specified with a G-value of 0.4 considering the risk of overheating during the summer months.

Thermal Mass Activation 4.3

Lightweight roof is proposed on High Meadow Infant School, the exposed thermal mass is not considering as a core part of any space conditioning strategy.

Space Conditioning Strategy 4.4 All the classrooms and teaching spaces shall be naturally ventilated using openable windows. There will be extract fans for ventilation in WCs.

Passive Design Solution 4.5 The passive design solution for this project is to minimise winter heat losses through a high standard of fabric performance and to maximise the use of natural light wherever feasible. Natural ventilation strategy minimises auxiliary energy consumption and the electrical strategy incorporates LED with daylight dimming in all occupied spaces. The combination of lowered demands and efficient delivery of services will reduce fuel consumption and therefore associated running costs and carbon emissions.



5.0 Dynamic Thermal Modelling

Introduction 5.1 The purpose of this section of the report is to provide the compliance/assessment evidence at the current design stage for: • Part L2A 2013 - CO2 Emissions • Local Planning Policy The thermal modelling work has been carried out using the dynamic thermal software developed by Integrated Environmental Solutions (IES) applied in High Meadow Infant School in accordance with CIBSE AM11 “Building Energy and Environmental Modelling”. It has been used to analyse different ventilation strategies and anticipate internal temperatures in different areas.

3-D view of High Meadow Infant School from Thermal modelling software

HVAC System Efficiencies 5.2 The performances of the building HVAC services in the thermal model have been based upon the supplied design information as follows: ASHPs with Natural Ventilation • Efficiency : 350%

• Fuel: Electricity Electric heaters with Extract

• Efficiency 100% • Fuel: Electricity

• Specific Fan Power: 0.3 W/l/s

Domestic Hot Water • Efficiency : 95 %

• Fuel: Electricity



Electrical Services 5.3 The electrical services in the thermal models have been based on the information supplied as follows; • Electric power factor for the whole building: 0.9-0.95 • Lighting system has provision for metering: No

• Lighting system metering warns of “out of range” values: No

• Lighting luminaire efficacy: 80 lm/W LOR 1.0 • All the occupied spaces contain PIR detection Sensor;

• Power consumption of each presence/absence/daylight detection sensor 0.1 W/m2

Part L 2013 Compliance 5.4 In order to comply with Part L of the 2013 Building Regulations the Building Emissions Rate (BER) must be less than the Target Emissions Rate (TER). The CO2 emissions were evaluated based on as designed values where available and using proposed allowance for lighting and auxiliary energy in other instances.

Part L 2013 Summary



Compliance YES



6.0 Low and Zero Carbon Technologies This section of the report specifically assesses the feasibility of incorporating renewable energy technologies and establishes a solution that will meet the required standard of performance. It is important however to be aware that sustainable design in the built environment is a three stage hierarchical process. This report focuses on current design stage however all three stages will be continuously considered throughout the design process. Each technology will be considered by looking at: • The associated targets

• The feasibility of the site

• The feasibility of the proposed building • The technology restrictions

Targets International polices • UK commitment to 50% reduction in

carbon emissions by 2025 from 1990 levels

National policies • 15% energy from renewable energy by

2020 • Part L improvements on energy and

carbon standards Regional policies • Regional Spatial Strategies (RSS) OR

• WCC Planning Requirement Client • Budget • Maintenance

• Payback period - simple & equity



Building Energy Demand and Low Carbon Technology Contribution 6.1 In order to benchmark the proposed new development, energy demands and CO2 emissions data have been estimated from the proposed architect’s preliminary building layout. These estimated energy consumptions are indicative only at this stage. They will, however, be used as a guideline to assess the percentage of the building’s total energy consumption and CO2 emissions that can be reduced or offset by applying suitable renewable and/or low carbon technology energy options. The following fossil and electric building benchmarks for existing building stock of the type of school have been established through a review of data from CIBSE benchmark data (TM46) and these figures should be reviewed as the design progresses. • Electricity consumption: 40 kWh/m2 ( benchmarks are based on Gross floor area)

• Fossil fuel consumption: 150 kWh/m2 ( benchmarks are based on Gross floor area) Taking account of the needs of the project, the following energy values are taken from initial thermal modelling calculations and have been defined as good practice.

electricity demand 33.59 kWh/m2 heating and hot water demand 22.89 kWh/m2

It is important to note that changes to the estimated energy use of the building would affect the percentage of the energy and CO2 reduction obtained by the renewable energy systems and may therefore affect the size and capacity of the renewable systems to be installed.

Low and Zero Carbon Technologies 6.2 ASHPs shall be used as primary heating strategy in the building with electric radiators in WCs and store rooms with minimal heating requirements. The table below shows the energy contribution by ASHPs which is 82.22% of the total space heating. This results in 4.4 MWh/yr saving in energy by ASHP which forms 25% of the total energy demand. This complies with the 10% energy generation from renewable energy in new major developments of North Warwickshire Borough Council.

ASHP Calculation

SCOP Heat efficiency 3.50

Proportion of Space heating met by ASHP (%) 82.22

Proportion of hot water met by ASHP (%) 0.00

Space Heating Demand Met by ASHP (MWh/yr) 6.15

Electricity used by ASHP (MWh/yr) 1.75

Total Regulated Energy Demand (MWh/yr) 12.38

Total Unregulated Energy Demand (MWh/yr) 4.78

Total Energy Demand (MWh/yr) 17.16

ASHP Saving (MWh/yr) 4.4

ASHP Contribution (%) 25.6



Considering Noise and Land Use 6.3

LZC

Technologies Noise and Land Use

Feasibility of exporting heat/electricity from the system

CHP unit

The foot print required would depend on the area of the individual units. Any mechanical plant should be considered against local noise requirements.

The CHP unit would be linked to the grid so any electricity generated by CHP unit could be sold back to grid or used in the building, and any heat exported to a district heating network, however, no existing network is available in this case.

Biomass

The foot print required would depend on the amount of wood chips/pallets storage for the system. Any mechanical plant should be considered against local noise requirements.

If biomass was used it would be sized for the peak heating load only, therefore no heat would be available for export.

Ground Source heat Pump (GSHP)

The loops could be installed either a horizontal / vertical arrangement.

If Ground source heat pumps were used, it would produce low grade heat, unsuitable for export to a district heating network.

Air Source heat Pump (ASHP)

The footprint required depends on the proposed number of ASHP units.

If air source heat pumps were used, it would produce low grade heat, unsuitable for export to a district heating network.

Solar Thermal An array of solar thermal panels could be mounted on the roof.

The heat energy generated by solar thermal panels could be used in the building and the excess heat energy could be exported, however no network is available in this case.

PV panels A PV panels could be placed on the pitched roof.

The PV array could be linked to the grid so any electricity generated by PV panels could be used in the building or could be exported back to grid.

Wind Turbines

The height of the turbines would be much taller than the building and the turbine blade diameter depends on the capacity of the electricity required. There is a potential for noise issues depending on the size and location of any local wind turbine.

The wind turbine could be linked to the grid so any electricity generated by turbine could be used in the building or could be exported back to grid.



Project Specific Technical Assessment Factors 6.4

Preliminary Assessment: CIBSE TM38 6.4.1 Each renewable technology is detailed and described with outline feasibility assessed using the methodology provided in CIBSE TM38: Renewable Energy Sources for Buildings. TM38 is an evaluation tool which provides an initial assessment of feasibility based upon the type of building, building location and building exposure. The output of the assessment includes weighting factors for cost effectiveness, carbon savings, marketing and technology risk. The output of the assessment is provided as a graphical representation of the results. Following the outline feasibility exercise the technologies deemed viable will be considered in more detail. All figures used are for a qualitative analysis to determine the suitability of each technology. Air source heat pumps have been reviewed as an addition to those considered by TM38. The strategic options which have been reviewed are as follows; • Solar thermal energy (hot water)

• Photovoltaics (PV) Cells

• Combined Heat and Power (CHP) • Ground water cooling

• Ground source heat pumps (GSHP)

• Wind power • Biomass boilers A summary of the feasibility process is snapshot in the diagram below. A more detailed description of each technology is given in Appendix A.

The results of the initial feasibility study indicate that photovoltaic panels and Air-Source Heat Pumps (ASHP) may be viable.

*Note - All the information listed in the graph above for illustration purpose only.



LZC Technologies appropriate to the site 6.4.2

LZC technologies

Brief Description Technologies Appropriate to the site

Reasons for excluding LZC technologies

Solar Thermal

The efficiency and implementation of solar thermal is dependent on the area, orientation and pitches of associated roofs.

No

This teaching block does not have a high hot water demand to install solar thermal panels.

Photovoltaics

Adequate orientation can be provided. Although its capital cost needs to be allowed for, a qualified Micro-Certification System which qualifies for FITs is likely to make it financially and technically feasible.

Yes

Photovoltaic panels are a viable option and the electricity generated by PV panels could be used in the building or could be sold back to grid during periods of low demand.

CHP

A CHP installation is effectively a mini on-site power plant providing both electrical power and thermal heat.

No

The hot water load profile was not considered sufficient, therefore CHP was excluded.

Ground Water Cooling

There is no current knowledge of ground water that is available for extraction on site via an abstraction licence. No

Programme does not support the surveying and ground works required and technical application would require significant financial outlay. As a consequence it is not considered economically viable.

Horizontal Ground

Source Heat Pumps

H-GSHP provides heating and cooling using the energy stored within the ground itself. Water is circulated through the ground via a horizontal trench.

No

The site is not suitable for a Horizontal GSHP.

Vertical Ground

Source Heat Pumps

Vertical (GSHP) provides heating and cooling using the energy stored within the ground itself. Water is circulated through the ground via a vertical borehole.

No

The site is not suitable for a vertical bore GSHP.

Air Source Heat Pumps

Air source heat pumps (ASHP) absorb heat from the outside to heat buildings. There are two types: air-to-air; air-to-water.

Yes

As there is limited gas on site, ASHPs have been used as the primary heating strategy.

Wind

There are typically planning obstacles in relation to wind turbines of the size that would be required.

No

Wind turbines ruled out due to site constraints and financial outlay.

Biomass

Modern wood-fuel boilers are highly efficient, clean and almost carbon neutral. Automated systems require mechanical fuel handling and a large storage silo.

No

The built up nature of the site does not provide suitable fuel storage space for a biomass boiler.

Financial Analysis and Payback 6.5 The calculations in this report are based upon the feasibility design data and as the design progress the inputs and results will be reviewed and updated if there is a significant change in the design strategy.



Assumed Utility Costs 6.5.1 The following utility costs have been assumed in order to assess payback periods:

Fuel Pence per unit kWh per unit Pence per kWh

wood chips 11p /kg 3.5 kWh /kg 3.1p /kWh wood pellets 21p /kg 4.8kWh /kg 4.4p /kWh liquid biofuel 69p /litre 10.3kWh /litre 6.7p /kWh natural gas 4p /kWh 1.0 4.0p /kWh electricity 13p /kWh 1.0 13.0p /kWh

Note: These prices are intended for guidance only. All prices are subject to variation with geographical region, order quantities, overall contract size and duration, time of year, delivery distance and time, etc.

Performance Analysis 6.5.2 To analyse the economic feasibility of each system three parameters were used: simple payback, CO2 reduction, and Energy Production. Simple paybacks represent the length of time that it takes for an investment project to recover its initial cost. The simple payback method, however, is not a measure of how profitable one option is compared to another. The simple payback should not be used as the primary indicator to evaluate a project, although it is useful as a secondary indicator to indicate the level of risk of an investment. Simple paybacks do not consider the time value of money or the impact of inflation on the costs. Payback periods can be important to small firms and where the organisation may simply need a faster return of its cash investment. It is also an indicator of compliance with the Building Regulations, Part L, that systems capable of achieving a simple payback of 15 years or less can be considered to be economically feasible and may be incorporated within the scheme as a measure to reduce the carbon rating of the building. To calculate these parameters certain assumptions on the future economics need to be used to evaluate future costs of energy, inflation and discount rates over the life of the system. The values assumed for the analysis were; • Discount rate: 3.5%

• Project life: 20-50 years

Energy Generated from LZC Energy Sources and Payback Periods 6.5.3 The financial and emissions calculations applied to the technologies found to be initially viable for the site and building profile demonstrated that all considered systems could be considered viable solutions for High Meadow Infant School. Photovoltaics and ASHP, however, are considered to be the most feasible solutions. ASHPs were chosen as the primary heating strategy due to limited availability of natural gas on site. With the use of ASHPs, the requirement for a 10% contribution from low or zero carbon sources has been achieved. The simple payback period for ASHP was calculated against a baseline of the existing gas fired boilers as a heating source, and will achieve payback within 15 years. Photovoltaics will not be taken forward as part of the LZC solution for this project due to all criteria being satisfied by the proposed ASHP system.



7.0 Conclusions The High Meadow Infant School has been designed to be a sustainable and energy efficient building year-round. This feasibility study and dynamic thermal modelling exercise has demonstrated that in order to meet the requirements of the North Warwickshire Borough Council it will be necessary for the High Meadow Infant School to include ASHP installation providing spacing heating in addition to the energy efficient fabric and fixed building services as specified in the design process.

Energy Consumption

(MWh) Carbon Emissions

(tCO2)


12.4 17.3

Part L 2013 Compliant

14.2 18.2

Part L 2013 with ASHP Installation



Improvement over Part L2A 2013 5.2%



Appendix A Renewable Energy Options



Solar Thermal Background Solar hot water heating is typically used to meet a proportion of the domestic hot water demand. The systems use a heat collector, generally located at roof level on support frames, orientated in a southerly direction to maximise solar heat absorption. It is also possible to install solar tracking panels that maximise hot water generation. The year round demand for domestic hot water will improve the viability of a solar thermal installation and is better suited to buildings which have medium demands for hot water. The two commonest forms of collector are panel and evacuated tube. The panel type collectors are generally more robust and reliable while manufacturers claim that the evacuated tube versions offer better winter all-round performance. Strengths • Simplicity and increased efficiency over secondary circuits through reduction of heat

transfer loss; • Demands other than space heating (which is not usually required during the summer)

help to match the demand for heat to the availability of solar energy;

• The fuel is free and the running costs are generally very low. Weaknesses • They are subject to freezing unless the water is drained-back when the pump

switches off, which puts constraints on the positioning of the collectors in relation to the feed tank;

• As new water continually flows through the collectors, they can be prone to ‘furring’ in the collector waterways resulting in loss of efficiency;

• High initial capital investment in comparison with conventional forms of domestic hot water heating.

Design The efficiency and implementation of solar thermal is dependent on the area, orientation and pitches of associated roofs. • Initial feasibility score 0%



Photovoltaic Panels Background Photovoltaic cells harvest that same energy to generate electrical power. Modules can be mounted on frames or incorporated directly into the building fabric ideally at an incline of 30º to the horizontal for maximum energy yield. Photovoltaic roof tiles are available which can be fitted in place of standard tiles. It is essential that the panels remain un-shaded, as even a small shadow can significantly reduce output. Photovoltaic panels are available in a number of forms including mono-crystalline, polycrystalline, amorphous silicon (thin film) or hybrid panels. The individual modules are connected to an inverter to convert their direct current (DC) into alternating current (AC) which is usable in buildings. Strengths • PV systems can be designed for a variety of applications and operational

requirements; • PV systems have no moving parts, are modular, easily expandable and even

transportable in some cases;

• The fuel (sunlight) is free, and no noise or pollution is created; • In general, PV systems require minimal maintenance and have long service lifetimes. Weaknesses • The primary limiting factor for this technology is the relatively high cost for PV

modules and equipment; • In some cases, the surface area requirements for PV arrays may be a limiting factor. Design Adequate orientation and roof space can be provided, as such PV panels are a viable option and the electricity generated by the panels could be used in the building or could be sold back to grid during periods of low demand. • Initial feasibility score 100%



Combined Heat and Power Background Combined Heat and Power (CHP) is an efficient, clean and reliable approach to the simultaneous generation of usable thermal energy and electrical power from a single fuel source. CHP is strictly an energy efficiency measure rather than a renewable energy technology. Due to the utilisation of heat from electricity generation, and the avoidance of transmission losses because electricity is generated on site, CHP is able to achieve a significant reduction in primary energy usage compared with power stations and heat only boilers. The viability of CHP is dependant upon the building base load requirements for both heat and power. 24 hour buildings with high heat demands and constant power demands lend themselves to CHP. The lower domestic hot water demand by comparison at this site does not provide sufficient heat sink for this technology. Strengths • CHP provides security of electricity supply;

• Local generation of electricity is usually cheaper than buying off-grid;

• CHP has the potential to provide carbon savings; • Excess electricity can be sold to the grid (‘net metering’). Weaknesses • The noise levels associated with a CHP installation should not be overlooked;

• CHP is inefficient for short run cycles;

• High installation costs; • Some CHP units are heavy - requiring solid flooring. Design A CHP installation is effectively a mini on-site power plant providing both electrical power and thermal heat. • Initial feasibility score 0% The hot water load profile was considered sufficient to install CHP in this building.



Ground Water Cooling Background Ground Water Cooling is a way to cool buildings without mechanical refrigeration. Subject to tests on the ground local to the site there is potential to utilise a closed loop (pipework as a collector loop) or open loop (pumping water directly from below ground) system which could be used as a heat sink/cooling source. This would be used in the slab cooling system to assist the natural ventilation strategy during the peak cooling season. The system provides an alternative to conventional air conditioning without the adverse environmental impact and potential health issues associated with it. It ensures a comfortable indoor environment whilst keeping energy and maintenance costs to a minimum. The performance of the system depends on a number of variables, including the climatic conditions, the diameter, length and depth of the underground tubes, the type and humidity of the soil and speed at which the air passes through the tubes. Strengths • Ground sourced cooling systems cannot be seen from the outside of the building so

aesthetic design is not an issue; • The system provides sound attenuation and is therefore useful where high external

noise levels preclude the use of windows for ventilation; • Significant running cost savings compared with conventional chillers. Weaknesses • There must be is access to suitable ground aquifer;

• Cost of system will depend on the size of the required buried pipe system and ground conditions;

• A ground cooling system is not a wholly renewable energy source as it requires electricity to drive the pumps;

• If an open loop system is the preferred option, a licence will need to be obtained from the Environment Agency to be able to extract the water and a test bore hole will also need to be drilled. Drilling the test borehole is expensive, particularly if the ground water source turns out to be inadequate.

Design The building has a low cooling requirement and the ground works required and technical application would require significant financial outlay. As a consequence it is not considered economically viable.

• Initial feasibility score 0%



Vertical Ground Source Heat Pumps Background Vertical ground source heat pumps (GSHP) offer an environmental friendly means of providing heating and cooling using the energy stored within the ground itself. Water is circulated through the ground via a vertical bore hole and, taking advantage of the almost constant temperature of the ground below a certain depth, absorbs heat from, or dissipates heat to, the surrounding earth. The water temperatures generated by GSHP do not achieve the levels associated with traditional Low Temperature Hot Water (LTHW) and chilled water systems they are ideal however for under-floor heating and cooling applications. A ground source heat pump could also be used to serve a traditional fan-coil or radiator system, but the lower operating temperatures will result in the output devices having to be significantly over-sized to achieve the level of cooling or heating required. The viability of the vertical borehole solution will be dependent upon whether the ground is suitable for such boreholes to be drilled, and a ground investigation would need to be undertaken to determine this. Strengths • Efficient renewable heating and cooling systems; • Carbon savings currently appear to be marginal, but positive if systems are driven by

renewable electricity; • Life expectancy of 40+ years for bore-hole pipes, 10-15 years for heat pump system. Weaknesses • Relatively high installation cost;

• Electricity drives the heat pump;

• If heating hot water, an ancillary electrical coil is required; • Large site area required for horizontal pipe installation. Design The confined nature of the site meant that this technology was considered not feasible at the first stage assessment. • Initial feasibility score 0%



Horizontal Ground Source Heat Pumps Background Horizontal ground source heat pumps (GSHP) offer an environmental friendly means of providing heating and cooling using the energy stored within the ground itself. Water is circulated through the ground via a horizontal pipe coil and, taking advantage of the almost constant temperature of the ground below a certain depth, absorbs heat from, or dissipates heat to, the surrounding earth. The water temperatures generated by GSHP do not acheive the levels associated with traditional Low Temperature Hot Water (LTHW) and chilled water systems they are ideal however for under-floor heating and cooling applications. A ground source heat pump could also be used to serve a traditional fan-coil or radiator system, but the lower operating temperatures will result in the output devices having to be significantly over-sized to achieve the level of cooling or heating required. Whether of not a horizontal system can be considered is dependent upon the space available on the site and local ground conditions. As a rule of thumb, a system using a horizontal pipe coil requires somewhere in the region of 10 metres of pipe coil per kW of heating/cooling to be provided. It is therefore considered impractical for very large projects, unless there is a significant landscaped area under which the pipework can be concealed. Strengths • Efficient renewable heating and cooling systems;

• Carbon savings currently appear to be marginal, but positive if systems are driven by renewable electricity;

• Life expectancy of 40+ years for bore-hole pipes, 10-15 years for heat pump system. Weaknesses • Relatively high installation cost; • Electricity drives the heat pump;

• If heating hot water, an ancillary electrical coil is required;

• Large site area required for horizontal pipe installation. Design The heating demand within the building and the open nature of the site meant that this technology was considered feasible at the first stage assessment. • Initial feasibility score 0%



Air Source Heat Pumps Background Even cold air is full of energy and air source heat pumps use the freely available heat in the ambient air to provide efficient heating and hot water at air temperatures as low as -25°C. Because the source of heat - the air - is abundantly available all around us, air source heat pumps have the advantage of low installation costs and minimal space requirements, while relatively mild winter temperatures in the UK mean excellent levels of efficiency and performance are achieved throughout the year. Strengths • Efficient renewable heating system;

• Carbon savings currently appear to be marginal, but positive if systems are driven by renewable electricity;

• Life expectancy of 10-15 years; • Can be utilised all year round between +35°C and -25°C;

• Always available and inexhaustible source of heat;

• No requirement for the cost and land area of ground collectors; • Ideal for new build or retro fit applications, especially where space is limited;

• Can be used for heating, cooling, domestic hot water and swimming pools. Weaknesses • Relatively high installation cost;

• Electricity drives the heat pump;

• If heating hot water, an ancillary electrical coil is required. Design The heating demand within the building meant that this technology was considered feasible at the first stage assessment. • Initial feasibility score 100%



Wind Power Background The power contained in moving air has been harnessed to provide energy for a variety of processes over hundreds of years. Wind represents a vast source of energy, and the UK has the largest potential wind energy resource in Europe. Wind power is currently one of the most developed forms of sustainable technology, and offers a cost-effective source of renewable energy. Wind generation equipment operates on the basis of wind turning a propeller, which is used to drive an alternator to generate electricity. Small scale wind turbines are typically in the range of 1kW - 15kW, with rotor diameters of 2.5m - 9.0m respectively. These systems can be stand-alone or, in some cases, building mounted. The efficiency and effectiveness of wind turbines depends on many factors, not least the average wind speed and wind pattern of the proposed site. Exposed sites, free from obstacles such as buildings and greenery, are more viable than sheltered sites. Column mounted (stand-alone) wind turbines installed at a suitable height above the building line are more effective than wind turbines located at roof level. There are often some planning difficulties associated with the use of wind turbines. Background noise and a phenomenon known as shadow flicker are also potential issues. Ideally, a small-scale wind turbine should be located at least 100m from the nearest neighbour to avoid any issues with noise or shadow flicker. Typical noise levels measured 20m from the base of an operating 5kW wind turbine (both upstream and downstream) in the range 4m/s to 8m/s are 48 - 50dB(A). At 100m, the predicted noise level would be below 35dB(A). The use of wind turbines is often seen as an obvious statement of a development’s dedication to the use of sustainable technologies. Design There are typically planning obstacles in relation to wind turbines of the size that would be required to provide a significant contribution to the building energy demand. The average local wind speed is 4.6 m/s, lower than the minimum recommended. • Initial feasibility score 0%



Biomass Boiler Background Biomass boilers provide heating through the combustion of fuels from sustainable sources, such as wood chips, wood pellets or peat. Modern systems are fully automated and offer an efficient and reliable way of heating a building. The systems typically available in the UK are of the wood burning variety, each of which has its own advantages and disadvantages in terms of the type of fuel being utilised. Wood chip burning systems can burn any type of dry wood waste, as long as it is of a certain size and moisture content, but typically requires a greater volume of storage and generates more ash than a wood pellet burning system due to the lower quality and efficiency of the fuel itself. Systems fuelled using wood pellets tend to require a smaller plant due to the more consistent calorific value of the fuel, but also tend to be more expensive to operate due to the manufacturing costs associated with the production of the pellets. A biomass CHP installation is an advanced technology and requires a suitable load during all operation, including in summer for it to be an effective measure. For this reason, an industrial application requiring process heat, or hotel or hospital is likely to be much more suitable than a purely domestic development. Small scale biomass electricity generation is a relatively low efficiency use for biomass, if the heat is not used profitably. Strengths • Biomass fuels "recycle" atmospheric carbon, minimizing global warming impacts since

zero "net" carbon dioxide is emitted during biomass combustion; • Biomass combustion produces less ash than coal, and reduces ash disposal costs and

landfill space requirements. Weaknesses • They are best suited for base load applications and therefore will need to be

supplemented with a high efficiency gas condensing boiler; • Systems require long-term planning for fuel supply and maintenance;

• Higher initial capital investment compared with gas boilers; • Fuel storage and feed to the boiler are an extra demand;

• Fuel costs are variable - dependent on source, distance from supplier and quantity purchased.

Design • Initial feasibility score 0% The constrained nature of the site access does not provide suitable fuel delivery access for a biomass boiler of a significant size.



Appendix B BRUKL Report

sustainable design statement for warwickshire county council

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