Winner of CIBSE Building Performance AwardProject of the Year (Public use) 2017Keynsham Civic Centre

Keynsham civic centre

Sustainability objectives

The new Keynsham Civic Centre has completely transformed the town centre in a way that usually accompanies new corporate office development. The redevelopment replaces outdated 1960s buildings, with a new Council office

The projecr aspires to the highest standards of passive environmental design and aims to be one of the lowest energy consuming public buildings in the country.

The Council wanted the sustainability focus to be on achieving exemplar levels of low energy and carbon emissions during actual operation. Therefore instead of a BREEAM assessment, the following requirements were set:

• Follow the Soft Landings Framework, with a two year aftercare period• ‘A’ rated EPC (Energy Performance Certificate)• ‘A’ rated DEC (Display Energy Certificate) by the end of the second full year of operation.

Our approach

Delivering low carbon in use requires a combination of low carbon design and reduction of the performance gap between design intent and operational reality. This requires working closely with the people who will use and manage the building.

We also used our Sustainability Matrix to set targets and communicate the vision to stakeholders to provide clarity on sustainability issues beyond energy.

Minimum Standard Best Practice Innovative Pioneering Notes

2010 Part L Regulation 2013 Part L Regulation 2016 Part L Regulation 2019 Part L - 'Zero Carbon' 'Zero Carbon' not yet fully defined

1 CO2 Emission design target 45 kg CO2/m2/yr 30 kg CO2/m

2/yr 15 kg CO2/m2/yr 0 kg CO2/m

2/yr “Carbon Neutral”Design stage target has to allow for unforseens in operational mode and changes in CO2 conversion factors. 20% allowance to achieve DEC rating.

2 DEC ratingC rating (38.3 - 56.33 Kg CO2/m

2/yr) B rating (19.5 - 37.5 Kg CO2/m2/yr) A rating (0 - 18.75 Kg CO2/m

2/yr) A+ rating Target DEC used rather than EPC - highly user dependent. Dec A rating for OFFICE = <18.75kgCO2/m

2/yr

3 Energy consumption

Heating & hot water load50 kWh/m2/yr 35 kWh/m2/yr 25 kWh/m2/yr 15 kWh/m2/yr

Lighting11 kWh/m2/yr 9 kWh/m2/yr 7 kWh/m2/yr 5 kWh/m2/yr

ITC Server & Cooling 75 kWh/m2/yrDesk PC

50 kWh/m2/yrThin Client & Partial Virtulisation

25 kWh/m2/yrThin Client & Full Server Virtulisation & Ramp Down

15 kWh/m2/yrThin Client & Cloud Computing

4 On site energy generation

Up to 20% based on local planning >20% on site renewables + provision for future low or zero carbon technology retrofitting >40% > 100% on site generation or agreed off-site generation

Stage C estimate is for renewables to offset 40-50% of CO2 emissions to achieve DEC A-Rating. BANES CORE POLICY CP3. Overall district renewable capacity to be 110MWe and 165MWth by 2026. No individual targets set. UK 15% target by 2020 noted.

5 U-values (W/m2K) Part L 2010 Limiting Values / With 25% Improvement

Wall 0.35 / 0.26 0.2 0.15 0.1

Average window 2.2 / 1.65 1.4 (Argon Fill, Warm edge spacer) 1.1 (Triple glazed windows, Argon fill and warm edge technology.) 0.8

Roof 0.25 / 0.19 0.18 0.12 0.1

Ground floor 0.25 / 0.19 0.18 0.12 0.1

6 Airtightness at 50 Pa 10 / 7.5 m3/h.m2

3 - 5 m3/h.m2 (BCO guide) 2 m3/h.m2 1 m3/h.m2 On average day 3 m3/h. m2 = approx fresh air requirements.

7 Building occupancy 50-80% Desks occupied at any time of working day.

hot desking/desk sharing for peripatetic staff. Cleaners/night-security aware of energy use

Hot desking, remote working, 24hour use restricted to small areas.

24 hour services - CCTV

8 Controls, metering and monitoring Seasonal Commissioning.

Produce DEC, report to senior management

Commissioning company retained to monitor over first year. Post occupancy evaluation. Action plan to respond to annual DEC

Responsibilities for reading, reviewing, actioning changes defined. Anonymised external reporting. Departmental energy targets

Continual monitoring, fine-tuning and feeding back. Results published to industry. Energy use reward/penalty system. Consider Formal external review.

9 User involvementFacilities Staff trained at building handover. Building Log Book provided with O&M Manual

Facilities staff involved in commissioning. Non-technical user guide produced and all staff inducted. Energy use fed back to users

Soft landing framework followed (see note)Interactive online user guide. Energy use on interactive display screen and / or online

Explore use of Departmental energy use as part of a departmental / personal carbon footprinting or trading (eg. WSP's PACT scheme)Consider non-technical user guide in accessible form such as 'mouse-mats'

10 Summer thermal targets for energy reduction

CIBSE / BCO design targets: Air conditioned Spaces: 24o C +/- 2oCNaturally ventilated: 25oC for <5% and 28oC for <1% working hours. External temperature to suit geographic location

BCO Design Targets used, test the design to UKCIP2020. Dress code partly relaxed in warm weather as ISO7730

Maximise adaptive comfort: internal temperature 2oC < external temperature when external temperature> 27oC, Dress code relaxed. Eg allow shorts and short sleeves in summer. Building design tested to UKCIP 2050

Dressing for the weather actively encouraged.Building design tested to UKCIP 2080

Highly dependent on how staff use the buildingReconsider when more info availableClimate project to use to be discussed

11 Thermal mass, ventilation and cooling

Natural ventilation where possible, otherwise mechanical ventilation and comfort cooling. VRV/VRF system used in Server room. Server room set point no less than 24oC

Thermal mass in roof. Natural ventilation plus low grade cooling or mixed-mode with heat recovery. Server room uses free cooling when possible

Natural ventilation with cooling upgrade strategy to deal with future hotter summers, mech vent with heat recovery. Ground Source and Free cooling and heat recovery to server and meeting rooms. Water cooled server racks.

Free cooling = directly coupled cooling

12 Solar controlProvide fixed external shading. Manual Internal blinds

Solar Control glass (>60% Light transmission, <45% Radiant Heat Transmittance) on South, East & West elevations. Orient and size windows for capturing useful daylight only - e.g high level rather than low level glazing.

Solar Control glass (>70% Light transmission, <40% Radiant Heat Transmittance) on South, East & West elevations. Automatic single motion external shading. Consider use of deciduous planting and provide upgrade strategy to deal with future hotter summers.

As innovative plus insulated shutters/blinds with reflective outer coating

13 Daylighting Average 2% daylight factor where possible. Views to outside. Glare control blinds

Narrow plan floorplate or rooflights to provide daylight. Views to sky. >2% average daylight to working plane.

Building form heavily influenced by daylight design. 80% floor area >2% average daylight factor

At least 80% of the floor area has an average daylight factor of 5%. Reflection onto vertical surfaces to reduce perceived gloominess. Building form led by daylight design

Design to CIBSE Lighting Guide 10, BS8206 Part 2 and the BRE Site Layout Guide 10

14 Artificial lighting and controls

300-500 lux to BCO and CIBSE guidelines. Fluorescent fittings throughout

300 lux background lighting plus task lighting. Daylight dimming and presence detection throughout building

150-200 lux background & wall-washing plus task lighting. Daylight dimming & presence detection. Timer Controls. As innovative with new lighting technologies eg. LED's

Incorporate learning from Lewis House refurbishment

15 IT strategyUsers encouraged to switch off PCs overnight. Kill switch for non essential peripherals. Servers ramp

down under part load. Consider laptops throughout

Thin client system – Terminal displays only with centralised computing power. All terminals switched off automatically out of hours. Servers running virtualisation software.

Off-site internet-based cloud-computing systemscloud-computing = software and resources provided by Internet on demand, like the electricity grid

Approximate values. Defined by A) The design Strategy; which is the base installed load and controls strategy defined by the design team, and B) The operation; which is under user control. BANES DRAFT CORE POLICY CP4. Keynsham is a district heat priority area. A thermal masterplanning approach is required here to maximise opportunities for district heating. Proposed heating and cooling systems to be selected in line with 'heat hierarchy'. ITC loads based on 1 person per 7.5m2 floorspace and non specialist servers. Regional servers can be discounted in DEC rating. Await BANES / MOUCHEL ITC equipment list.

User

and

Ope

ratio

nal

Inte

ract

ion

Build

ing

and

Ope

ratio

nal T

arge

ts

Proposed Building Regulations

Evaluations show actual performance KPI's (eg in energy and water), are usually much greater than those predicted during the design stage. Often a result of poor commissioning, training & management.www.softlandings.org.uk

KEYNSHAM TOWN HALL OFFICE SUSTAINABILITY MATRIX

Desi

gn c

onsi

dera

tions

and

stra

tegi

es

Sustainability Criteria

PAGE 1 OF 2: ENERGY CRITERIA

Extract from Sustainability Matrix

The four storey atrium Light floods into the internal space

Environmental design

We have adopted a ‘passive first’ approach to every aspect of the architectural and services design.

Orientation: Narrow floor plans (circa 15m) optimised for cross ventilation with elevations orientated north and south.

Form: Pitched roofs create a thermal reservoir and drive passive stack ventilation. Opening clerestory windows are set back from the façade to shield them from traffic noise. Roofs are pitched south for photovoltaics.

Structure: Hybrid frame where CLT significantly reduces embodied carbon while using precast concrete planks for 50% floor slab provides thermal mass.

Daylight: Larger windows to north facades maximise daylight without solar gain. Light shelves to the south facades bounce light deeper into the plan improving daylight uniformity. All glazing is fixed meaning blinds can control daylight without cutting out ventilation.

Acoustics: We incorporated a 150mm deep acoustic louver into a bespoke window system with an inward opening door behind.

Embodied carbon: We undertook a pre-contract embodied carbon assessment which helped the team to appreciate the impact that the materials embodied carbon had on the buildings full life-cycle carbon footprint. This helped the team to prioritise where to invest low embodied energy materials which gave the client best value for money. Cooling: Air conditioning was avoided throughout. In meeting rooms where heat gains are higher we used natural ventilation combined with acoustically perforated radiant aluminium cooling sails.

Ventilation: Voids were introduced to allow passive stack ventilation. There are high and low level vent doors, the bottom door is manually controlled and the top door is controlled by the BMS and provides both daytime ventilation and night purge.

Embodied carbon: We undertook a pre-contract embodied carbon assessment which helped to prioritise between passive and active investments for whole life-cycle carbon emissions.

01 Structure02 Daylight + Ventilation 03 Thermal Mass 04 Acoustics05 Ventilation 06 Lighting07 Acoustics08 Lighting 09 Day Lighting 10 Services Distribution

0102

03

04

0506

07

08

09

10

Specific environmental features include:

• 1150m2 photovoltaic panels providing 200,000kWh per year of electricity, 50% of target building emissions.

• ‘Waste heat’ from water cooled servers provide 20% of the building’s total heating energy requirement.

• The anticipated annual utility cost is £15,000 with an annual income of £23,000 from export of PV generated electricity and Feed-in-tariff (FIT), so a net annual income of £8,000.

Soft landings and dec a

The project is the first to target a Display Energy Certificate (DEC) A rating from the outset. To close the performance gap, we have fully adopted the Soft Landings approach at all stages, with the design team and contractor committed to two years of post-occupancy monitoring and support. This will include the use of seasonal commissioning and occupant surveys. During this period, the contractor is responsible for closely monitoring the energy use and optimising the performance.

As part of the DEC ‘A’ strategy, we developed an Energy Risk Register which identifies potential unregulated energy uses early in the design stages. This means they can be designed out where possible and monitored during occupation to minimise their impact on the energy costs.

An independent Commissioning Manager was appointed to ensure the building was thoroughly commissioned. They continue to be involved throughout the two year aftercare period.

There have been workshops with the building managers through design development and in the run-up to handover.

The project team were appointed in 2010 and planning was submitted in 2012. The project was tendered through a two stage Design & Build process based on a Guaran-teed Maximum Price with gain share incentive.

We wrote the industry’s first Soft Landings Employer’s Re-quirements, setting out various roles and processes that will contribute towards achieving the DEC A target. These requirements have since been incorporated into BSRIA’s recent publication “How to Procure Soft Landings”.

We developed an innovative Energy Performance Contract which included an Energy Budget that the design was to be completed within. The Energy Budget includes the assumptions that the energy modelling was based on, with a clear division of responsibility between those within the control of the contractor and those beyond.

This innovative approach aims to create an open and col-laborative environment that allows all parties to work to-wards the best outcome, while maintaining some accountability. It acknowledges shared responsibility.

procurement

Transport

Secure cycle parking is provided for 20 bikes alongside additional on street hoops for both bikes and motorcycles. Showers, lockers and drying facilities are provided. Over the next four years the council’s Green Travel Plan aims to include an increase to cycling, walking, bus and train use.

Energy Risk register

Post occupation evaluation The contractor is responsible for reviewing the energy performance on a monthly basis, identifying where this differs from the energy budget and explaining the difference. The project team is working together to optimise the performance over a two year period.

The chart below shows the actual energy use and PV generation for the first year of operation.

The chart above shows how ongoing commissioning has re-duced internal lighting consumption by a significant amount. There is an expected seasonal variation, overlaid with a downwards trend. Further improvements are ongoing.

Further evaluation will be carried out over the next year as part of a UCL study ‘Total Performance’ of Low Carbon Buildings in China and the UK’. This will include occupant surveys and monitoring of indoor environmental quality (thermal comfort, indoor air quality, acoustics and lighting).

Credits

Client: Bath and North East Somerset Council Architects: AHR

Environmental Engineer: Max Fordham Main Contractor:Willlmott Dixon

Structural Engineer: Hydrock Project Manager:Capita

Quantity Surveyor: Aecom Acoustician: Max Fordham

Images: supplied by AHR / Julian Anderson (photographer)

Awards (selected)RIBA South West Award for Sustainability

RIBA South West AwardBritish Council for Offices Best of the Best Award

Civic Trust South West Sustainability Award

further post occupancy studyThe chart below shows the DEC calculation on a rolling 12 month basis, where less than 25 represents an A rating and less than 50 a B rating.

This shows a continuing reduction over the period and we are confident of achieving our target in 2017.