Design achievements at Bathgate Partnership Centre
27.01.12
Building Description:
BDP led the design team for the new Bathgate Partnership Centre. The 2,550m² project for West Lothian Council was completed in summer 2011. Located on a prominent site in the West Lothian town, the proposal consolidates the previously dispersed council services under one roof.
The partnership ethos for the new building is based on a concept of a shared working space strategy, which will allow operational interfaces between the various stakeholders, providing users with a ‘one stop shop’. The ground floor of the two storey building houses a public library, advice shop, community centre and café, grouped around a double height street. The upper floor accommodates open plan offices for the various council departments, and allows for flexible working patterns by providing the occupants with a variety of meeting spaces and quiet areas.
A south facing enclosed garden and orchard to the rear of the building enables ground floor activities such as the library, café and crèche to spill out into a dynamic external space. The facades are clad in random cut Caithness flagstone and seamed brass to create a welcoming yet appropriately civic presence, and set a benchmark for future urban realm improvements in the town.
The building has a sedum roof and incorporates a small scale gas CHP system, natural ventilation including a solar flue to utilise the stack effect, a heat displacement and recovery system as well as a number of other energy reduction measures. It has an EPC rating of A.
Team:
Client: West Lothian Council
Architect: BDP
Structural Engineer: Halcrow Yolles
Services Engineer: Hulley and Kirkwood
Quantity Surveyor: Gardiner and Theobald
Contractor: Ogilvie Construction
Project management arrangements:
Most of the design team had recently completed the new Civic Centre in Livingston for West Lothian Council, which had utilised both active and passive sustainable features. One element of the brief for the Bathgate Partnership Centre was to build upon this experience of the design team, who had already an understanding of the low carbon ethos and principles, as well as the importance of services integration within the architectural design to incorporate low energy principles and to comply with the reduced carbon emissions targets as set out in the Building Standards(Scotland) Regulations and to comply with planning conditions which required a further 15% improvement to carbon emissions in relation to the BER.
To ensure progress, this was monitored at the Stage C and Stage D design reviews where the energy consumption was checked by an accompanying dynamic thermal model produced by Hulley & Kirkwood to allow energy and carbon emissions analysis. BDP and Hulley & Kirkwood worked together on pulling together a strategy which would meet the client’s aspiration for a high rating of EPC, which would meet and exceed the statutory requirements. Sustainability was an agenda topic at the regular client meetings which allowed progress to be monitored and new ideas to be tabled. West Lothian had their own internal sustainability advisor, who also attended these meetings and contributed to the process. The solution was then cost checked by the Quantity Surveyor to ensure it was affordable and cost effective. As this services strategy developed in parallel with the architectural design, it became embodied within it as opposed to appearing ‘bolted on’.
An example of this is the ‘serviced floor’ was developed, which incorporated the services from both the ground floor (via the ceiling) and first floor (via the plenum floor), which allowed the first floor ceiling to be free of services and to follow the sloping roof form allowing the stack effect to work along with the perimeter natural ventilation.
Delivery of low carbon designs with good internal environments:
Ideally WLC would have applied for BREEAM certification and looked at the possibility of this. The building was reviewed by BDP sustainability and would have achieved an ‘Excellent’ status and could have targeted ‘Outstanding’. However, due to the brief components, it was a ‘bespoke’ building which attracted additional costs. It was decided that the building could not afford the additional costs of this BRE accreditation, and that the formal benchmarking should be the EPC certification which is visibly displayed in the reception area.
The BREEAM review was, however, a useful checklist and was utilised as such by the design team who were able to utilise the recommendations of the BREEAM Health and Wellbeing credits (in relation to the physical internal environment) and were able to address issues such as daylighting and ventilation by the introduction of rooflights, large areas of north facing glazing and the lightscoop all to benefit the first floor workplace. Low VOC products and materials were also specified, and an acoustician was appointed to assist in the aural quality of the space, in particular the first floor office (which is open to the community facilities below) as many of the client stakeholders had not worked in such an open plan workplace environment.
The Hulley & Kirkwood dynamic simulation building energy model was therefore used as the main tool to review the building against the aspirations. The design team found this to be an accurate reflection of the buildings performance as it took into account orientation, building fabric and insulation, solar shading, glazing u-value performance as well as the mechanical and electrical services performances of heating and cooling. Part of this process included thermal modelling which was reported on specifically. This comprised a dynamic energy simulation which was performed to establish the Building Emission Rate to determine if compliance was met with the requirements of the Scottish Building Regulation Section 6 with regards to carbon emissions and the planning condition for a further 15% improvement to the BER. The proposed Stage C & D design buildings were simulated with respect to varying time dependant internal and external conditions affecting heat gains, bulk air flow movement & solar gain.
Adjustments to the proposed Architectural design and mechanical and electrical services were incorporated into the design as required by interrogation of the thermal model results to ensure compliance with the energy targets.
On completion of the construction of the building an Energy Performance assessment was carried out and the EPC rating of A was achieved.
Design energy model:
Hulley & Kirkwood’s experience and expertise led to the development of the low energy passive and mixed mode active solutions through extensive dynamic modelling.
PASSIVE DESIGN. Orientation and location - The site was fixed, and was a brownfield site in the centre of Bathgate. Being on the south side of an east west main street, it has a north facing main facade and a south facing rear facade and garden. These factors helped to determine the location of the building elements within the brief. The library requiring good even daylight was placed on the main facade and has a double height space to maximise the northlight. This strategy was also used for the main waiting area. On the south facade the main hall and meeting rooms were located, as they could open onto the gardens and were not as sensitive to high levels of light. Connecting these spaces is the street, which has an integrated light scoop bringing light into the centre of the plan and also utilising the stack effect in the double height space to extract the exhaust air. As the building sits on an elevated position an orchard was planted in the south facing garden to produce a micro climate for external use, shading to the south facing spaces, and a wind break before the building itself.
Form – Initially the design was developed as a standard naturally ventilated 15m linear bar, driven by the office accommodation. However the envelope to floor area ratio was very high, and the connectivity within the building, which the client wanted to maximise, was being diluted. This resulted in a more ‘compact’ form which had a deep plan. The elements within the brief were able to work well within this form, and as the building became 2 storey could be a single circulation core. This move produced a more efficient built form and optimised the costs.
Fabric – The fabric reflects the orientation in relation to the glazed elements, with large unrestrained openings in the north and lower level opening on the south, giving good views out and daylight but minimising solar gain. A steel frame was chosen due to the large spans required. The building uses a restricted elevational materials pallet of Caithness stone, brass and timber.
ACTIVE DESIGN - The dynamic energy simulation (thermal model) was performed to establish the Building Emission Rate for the new Bathgate Office & Council Facility for West Lothian Council to determine if compliance is met with the requirements of the Scottish Building Regulation Section 6 with regards to carbon emissions. The proposed building was simulated with respect to varying time dependant internal and external conditions affecting heat gains, bulk air flow movement & solar gain.
The accuracy of the model, and hence the validity of any proposals, are governed by the assumptions made and the resolution of the model’s geometry. The model’s geometry was accurately drawn from information supplied by the Architect. Assumptions on the occupancies and internal heat gains were based on typical values for specific operational area usage.
ACTIVE DESIGN
General
The philosophy for ventilation is predominantly natural, however where mechanical ventilation is necessary a Variable Air Volume Displacement Ventilation with heat recovery strategy is employed to provide a low energy/low carbon solution.
Heating is provided by modular high efficiency low Nox rated condensing atmospheric gas fired boiler plant via a constant temperature circuit to AHU plant (two off) and a compensated heating circuit to heat emitters.
A small scale gas fired CHP unit (35 kWe) provides base heat load through engine heat recovery, with power utilised on site to displace a proportion of grid supplied electricity to contribute to the required LZCT on site for compliance with Section 6 Energy & Carbon Reduction targets. The thermal modelling, energy & carbon emissions report confirm that the CHP Unit is an absolute necessity to comply with Section 6 Building Regulations.
Domestic hot water shall be generated via an LPHW plate heat exchanger and buffer vessel arrangement, also taking advantage of CHP engine heat recovery.
Internal Conditions
The various operational zones were subject to typical internal gains determined from expected equipment and occupancies. The internal gains specified are controlled via daily schedules. It is assumed that all lighting, personnel and equipment gains are active during normal working hours of between 08:00 and 18:00 and that all gains are inactive at all other times.
External Conditions
The design building was simulated with respect to statistically predicted weather data, set to Glasgow as per Section 6 requirements, and the local solar path, determined by the location and orientation of the site.
Space Conditioning Systems
The building is to be ventilated by a combination of natural and mixed mode ventilation. All zones incorporating natural ventilation have a window opening free area of at least 5% of the zone plan area, and have trickle ventilators of 12,000mm2. All internal zones are mechanically ventilated with a supply air volume of 12ls-1/person.
The main hall is fully naturally ventilated by means of manually opened windows and by two “wind catcher” natural ventilation chimneys with an opening area, i.e. the area for free air movement, of 5% of the room plan area. A manually operable trickle ventilator of 12,000mm2 has been included to provide minimum fresh air when windows are closed. Wind catchers also provide continuous trickle ventilation.
Natural ventilation in all open plan areas, ie the first floor office spaces and the main library is assisted by local displacement ventilation terminals. This arrangement will provide both cross and stack ventilation air movement in to adjacent zones, thereby preventing the maximum temperatures from rising significantly above the ambient when windows are opened.
The central atrium is served by mechanical extract ventilation, which will draw air from adjacent zones further promoting cross ventilation.
The simulation assumed that in summer occupants will open available natural ventilation apertures at an internal temperature set point of 22 degrees Celsius. The actual conditions experienced in the building depends on their correct operation, for example, non-opening of manually opened windows during hot weather will allow the air temperature in the rooms to rise above the figures suggested by the simulation.
A VFR heating & cooling system was incorporated to describe the following areas;
- Internal Meeting Rooms
- Staff Break-out areas
- Mail room
- High Density IT areas
- Weights Room
- Fitness Suite
- Flexible Hall
High efficiency low NOx condensing gas fired boiler plant shall be located in the basement boiler room and be modular type for flexibility. The boilers shall work in tandem with the 35 kWe gas fired CHP engine with which recovered heat shall be utilised to satisfy base load demand on heat and power.
Heat Recovery of Exhaust Air
The ventilation air handling plant incorporates plate heat exchangers which will recover heat from the extracted air and utilise this to pre heat the incoming fresh air supply. The heat recovery effectiveness is estimated at 65%.
Lighting Levels
The simulation predicted that zones with heavily glazed façades will benefit from a reduction in lighting levels compared to the notional building. In addition, installed lights are energy efficient.
The lighting systems incorporate fluorescent fittings with high frequency controls and a lighting control system with dimming available in areas with daylight linking. Feature lighting is also provided in specific public areas.
Lighting management in the form of daylight linking, presence detection and automatic time controls are provided to ensure that the building has a simple, flexible, easy to use, and energy efficient system.
Automatic Controls and Building Management System and Metering, Monitoring and Targeting System
All mechanical services, including boiler plant, VRF air conditioning plant, pumps, air handling plant and fans are controlled by an automatic control and building management system. The system provides optimum start and stop programmes, zone controls, frost and fabric protection, maximum flexibility in plant running and monitoring of plant operation and alarm functions. An interface with the electrically operated auto opening roof windows is provided to allow integration of operation with the energy efficiency strategies. Comprehensive metering of electrical distribution and HVAC plant is provided and integrated with an MMT system to ensure energy use is properly monitored, managed and where possible reduced year on year.
The ventilation control strategy comprises supply and extract air handling units with variable speed controls, heat exchanger for heat recovery and LTHW heater battery and frost protection coils.
The system supply temperature shall be controlled by the heating coils control valves via multiple zone temperature sensors in the areas served and the AHUs shall have full frost and low limit temperature sensors for system protection.
A night purge facility is provided such that should the internal space temperature be greater than 18ºC out with normal operation hours, the supply and extract fans shall operate to cool the space temperature to 14ºC (head end adjustable) using lower temperature ambient air at 14ºC or above.
With ambient air temperature less than 14ºC, night purge shall comprise operating exhaust AHUs only in conjunction with external actuator operated windows opening under the dictates of the BMS night purge signal. The purge is disabled when internal space temperature drops to 14ºC.
RENEWABLE ENERGY
The building design strategy incorporated passive design of the structure to minimise energy usage rather than the incorporation of renewable energy systems. This strategy focused on designing out energy usage which required extensive energy modelling during the design development.
A Combined Heat & Power (CHP) Engine (LZCT technology) was installed at the development since there was a steady base load demand for electricity within the Council Offices facility created by the computer systems which require to be in operation continually. This base load of 35 KWe was used as the sizing criteria for the CHP and subsequently the heat output from the unit is utilised to generate domestic hot water and/or supplement the space heating system.
The residual heat from the CHP being utilised this way subsequently reduces the demand from grid supplied power by generating on site power from natural gas, thereby reducing the carbon emissions and overall cost of energy consumed.
Efforts made to reduce energy consumption in operation:
The design of the building services incorporated the principle of reducing energy consumption during the operation of the building by the in facility to meter the various systems for energy usage. This function is provided by the Building Management System which automatically records the energy usage of the various mechanical and electrical systems. By regular monitoring of these meter readings the building user will acquire the required knowledge to quantify the energy usage and identify possible savings. This facility will provide the opportunity to motivate the building user to minimise energy usage and reduce annual running costs year-on-year.
During the design development of the project the Hulley & Kirkwood dynamic thermal model was re-assessed on a number of occasions to ascertain methods of improving the thermal performance of the structure. Various options were considered and applied comprising the following:
Improvements in the U values to minimise heat losses.
Reduction in areas of glazing while achieving the requirements of the Building Regulations and maintaining the principle of a mixed flow ventilation strategy incorporating natural ventilation elements.
Integration of the building services in a manner that minimised the service zone requirements and therefore kept the structure height to a minimum which correspondingly minimised the surface area/heat losses/quantity of materials.
Incorporation of bris-soleil at south facing glazing to reduce heat gains.
The building energy target was significantly lower than previous standards set by the Building Regulations and planning conditions. The design which was developed met these stringent requirements and also incorporated LZCT technology to provide renewable energy on site therefor reducing the utility energy demands.
By generating the base load electricity within the development the quantity of electricity required to be delivered from the national grid was reduced and the annual utility costs were subsequently minimised due to the current utility pricing strategy where natural gas is less expensive than purchasing electricity from the national grid.
Various options were also investigated with respect to purchasing the CHP outright or entering a hire/purchase scheme. It was decided that purchasing of the CHP was the most economical option and suited the client’s financial strategy for this project.
The planning requirement of improving on the TER by 15% presented a challenge which was overcome by the incorporation of various measures to reduce the energy consumption as detailed above. The resultant improvement on the TER by 23.2% indicates a significant standard of construction and thermal performance.
Steps taken to ensure that the building was constructed in a sustainable fashion:
In terms of the actual construction process, the main contractor was part of the Considerate Contractors scheme which carries environmental responsibilities in terms of waste materials, water usage and recycling. A waste management plan was implemented and monitored in terms of the actual new materials brought onto site.
As the site was brownfield, there was an existing council building on the premises. This was demolished and suitable material was crushed on site and used for backfill. The engineer also worked with the architect to determine the levels to optimise the cut and fill process to keep as much material on site as possible to reduce land fill. The architect was also able to retain the car parking area and existing retaining wall on the west of the site and successfully integrate them into the design.
With the landscape design, there were a considerable amount of trees on the site, a landscape strategy retained the majority of these and replanted new fruit trees as part of the orchard, with the view that the community groups could make jam and chutney. The sloped roof was specified as a sedum roof as this was visible due to its form, and it also acted as an attenuation system in the rainfall, and the landscape architect chose the species to encourage biodiversity. The landscape plan was designed in relation to the Ecology credits within BREEAM, which was still being considered during the design process.
The external elevations of the lower floors is a cut Caithness stone. This is randomly sized and by-product of Caithness paving flag stones used in Edinburgh etc, and was a very economical material. The sawn edge was expressed and the stone gives the building the desired civic presence within the town. On the garden facade a locally sourced FSC certified timber is used, which gives a very tactile and soft feel to the public spaces which open out onto the orchard. The first floor uses a brass seamed cladding, which the design team had used at the West Lothian Civic Centre. Again this proved to be a very durable and economic material in relation to its close alloys of copper and bronze This brass is 100% recyclable and its longevity and low maintenance, as well as its aesthetics made it attractive.
Internally, the building is simpler, using linoleum for the areas with underfloor heating, white plasterboard walls, and a timber panel system to accentuate details such as the ‘broch’ which contain the meeting rooms on the first floor and IT suite on the ground.
Feedback on quality of occupant experience:
Community consultation on this project commenced 4 years in advance of its build. There were potentially sensitive local issues specific to the proposed closure of five local buildings to allow the progression and build of Bathgate Partnership Centre. These outlying buildings included a library, Community Centre, Registrar’s office, Advice Shop and an Adult Basic Education facility. These facilities are now collocated with the partnership centre within the heart of the town centre with excellent public transport links. The former buildings were proving difficult to maintain and inefficient to heat and not catering for the specific needs of our customers.
The consultation process has involved over 70 local community groups including community users, Town Centre Business (Enterprising Bathgate) Church Groups, Schools, Residents associations, Community Council and members of public. The community and environmental benefit that co - locating would bring to Bathgate was discussed and firm community support for the plan was evident.
The consultation process continued throughout the project and at several stages of the build programme, local community groups were invited to tours of the site. In excess of 400 people witnessed progress and comments were extremely positive throughout. Towards the later stage of the build community groups were invited onto to the roof to witness our green Sedum roof being laid. This element of the project generated significant local interest.
Bathgate Partnership Centre has seven main purposes, they are namely:
• Staff accommodation for 95 staff members previously located at the five other offices within town.
• Community centre that supports over 70 local groups.
• A front of house council service that delivers customer services including Advise Shop, and Payments Office
• Bathgate (Simpson) Library
• Registrars Service – Performs weddings and registers births, deaths and marriages.
• Other council services including Social policy and Adult Basic Education have staff located and deliver services from the building.
• Community Cafe – providing healthy option foods and a supporter of Bathgate Fairtrade.
Currently we are averaging 18,000 visits per month to Bathgate Partnership Centre accessing the wide range of public and community services that we deliver.
Occupant Experience:
Feedback from users of the facility has been overwhelmingly positive since we opened to public on 15th September. Much of the feedback has been specific to the quality of the build and the benefits to customers from delivering important services within one centrally located building. Representatives from the Community Users group “Bathgate Community Centre Management Committee” were invited to the monthly project board meetings, participating fully in discussions.
Specific Feedback has included:
Billy Weir, Chair, Bathgate Community Centre Management Committee, wrote in a recent Partnership Centre Newsletter – “Many thanks to all those involved in the planning and delivery of this excellent project and in the strong links that have been established with community groups and public in what has been a very exciting project and the overwhelming response from our user groups this far has been extremely positive.
I congratulate West Lothian Council on delivering an excellent community facility and for the process they adopted in ensuring we were fully involved throughout”.
David Stein, Chair, Enterprising Bathgate, home to Scotland’s First Business Improvement Districts (BID’s) “I would like to comment on the achievement of West Lothian Councils new civic partnership building in South Bridge Street, Bathgate.
It is commendable to see so many great community resources at the heart of our own centre, with all these functions under one roof the benefits to the local economy will be tangible, previously persons wishing to use these services were diluted on the outskirts of the town centre providing little or no benefit to the local economy.
Not only do we have a fantastically functional and beautifully designed building but i feel we now have a focal point or hub which has been lacking for so long”.
Alan Cunningham, Manager Bathgate Partnership Centre Advice Shop – “We have a standing item on our monthly team meeting agenda – ‘Partnership Centre issues’. Every month staff comment how much they like this building and how much our customers like it. It’s because it’s comfortable modern and light and this has helped create a really good, friendly atmosphere. The Advice Shop team love it”.
Capital Costs - Gardiner & Theobald provided cost advice from the start of the design process to ensure that the sustainability and energy efficiency requirements were achieved while also maximising value for money in capital cost.
Early in the design process various options for the geometry of the building were considered. The final choice resulted in a lower external wall area to floor area ratio than some of the other options which reduced the cost of the external envelope. A single vertical circulation core was required for the selected design while other options that were considered would have required more than one core.
Extensive research was undertaken at an early stage into the materials to be used for the fabric of the building with advice being obtained from specialist suppliers. This allowed materials to be selected that were cost effective while still satisfying the requirements of West Lothian Council and the design team.
The sloping aspect of the site meant that careful consideration was required for the ground works and underbuilding. Suitable material was processed and recycled from the previous building on the site which had been demolished and this material was used to assist in achieving the correct levels over the site. This approach had both cost and sustainability benefits compared to importing material on to the site. The extensive green roof was a cost effective method of reducing rainwater run-off and providing thermal insulation benefits.
Similar to the approach for the building fabric extensive work was undertaken on the Mechanical and Electrical services at an early stage in the design process to ensure capital expenditure was not adversely affected by the energy efficiency requirements. Integration of the services with the structure of the building ensured that costs associated with builders work for services was minimised. Concentration of services distribution within the ceiling void at ground floor level and the raised access floor at first floor level reduced materials required and associated costs.
Life Cycle Costing – There was no overall calculation for LCC. However an in-depth analysis was carried out on the CHP system as a leased option (Energy Purchase Scheme) with ENERG, which would involve no capital outlay for the council. Ultimately the CHP became part of the tender price and the projected energy savings were conservatively estimated at 10-12%, and with maintenance included gave a payback period of 8 years. This was based on 2008 energy costs, and it is anticipated this period would be shorter using 2012 energy costs.
Running Costs – In providing a one-stop-shop by effectively combining five separate buildings, the running costs have been considerably lower than those the individual buildings. Projected running costs were calculated in relation to the CHP (using 2008 energy costs). The actual running costs are higher, primarily due to the success of the building which is open 6 days a week and from 8am to 8pm daily. The building usage patterns and the actual electrical load of the building had not been established. Based on a pro rata basis the kw/h usage is in line with what was anticipated.
At this time there are no whole year records of the actual building running costs, as it has been open less than one year.
