hillcrest housing association hq. - a&ds

Hillcrest Housing Association HQ. Case Study produced by the A+DS Sust. Programme.

Hillcrest Housing Association Headquarters

A new headquarters building intended to reflect the company’s core commitment to sustainable development and to be an exemplar of ‘environmentally sensitive architecture’.

BACKGROUND

First set up in Dundee in 1967, by 2005 Hillcrest Housing Association had grown to 600-700 staff, managing over 6000 properties. They had offices in Arbroath, Perth, Glenrothes, Crieff and Edinburgh, as well as Dundee. Their headquarters was based in a 1970’s building built for a jute company in the centre of Dundee. The building was becoming dilapidated, and Hillcrest also needed more space for their staff. Having looked at improving this building, converting other buildings, and a number of sites for possible new buildings, the company took an option on part of a site owned by Scottish Enterprise on the Dundee Technology Park, some 3 miles west of the city centre. While the conversion options looked expensive, some of their existing sites in the city centre could be easily sold if operations were brought together into a new building, and the company were attracted to having a new headquarters building that could act as a good image for the company’s go-ahead nature. Originally established to convert old Dundee properties into flats, the company began building new houses and flats in 1990.

In addition to creating a new headquarters, the company wanted to bring several different departments, then in separate buildings, under one roof, to amalgamate services, be more efficient and to increase synergy within the company and reduce separation between departments. The new building would serve solely as company offices, with the Dundee housing office where tenants would come to pay rent or discuss tenancies remaining at Camperdown Street at the docks in the city centre.

APPROACH

As a company that not only provides houses but supports communities, Hillcrest sees sustainability as a core element of their business. At the outset of the project to create a new company HQ they agreed an ‘Aspirational Environmental Brief’ which stated the following:

‘Hillcrest seeks to ensure that all the association’s activities have a minimal or positive environmental impact, and make a positive social and economic contribution to local communities. The project should reflect the Hillcrest commitment to the principles of sustainable development. Hillcrest aspires to build the ‘greenest’ building in Dundee, a building at the forefront of sustainable design that can function as a working exemplar of environmentally sensitive architecture.’

With the company focused on creating a new building, they interviewed 6 architects, introducing them to the project and inviting their reaction. Nicoll Russell Studios (NRS) were known to the company, and had done some design work for them before. NRS are well known in the Dundee/Fife/Angus area for cultural buildings such as Dundee Rep and the Byre Theatre but also had extensive experience of work for commercial clients, including two other buildings (‘Grianan’ and ‘Prospect 2’ Office Buildings)

Concept sketch of main internal space

Main atrium of building

External view from South


Ground floor plan


on the Technology Park not far from the site Hillcrest had identified for their building.

Once appointed, NRS’s first commission from Hillcrest was to fully analyse the options for conversion of existing buildings, and for new buildings in Dundee city centre and on the site on the technology park. This process confirmed that building on this site was the best option for the company in terms of value and result.

The brief for a new building at that stage was simple, with a rough schedule of accommodation, the notion of bringing core staff and services together in one building, and to bring different departments together into a closer working relationship. NRS then spent time analysing the company’s preconceptions and requirements and building a detailed brief. This process was greatly facilitated by two of the Hillcrest directors most involved with the process not only being well known to NRS but also having been trained as architects; this led to NRS finding it easy to establish trust and a shared vocabulary with the client.

This process clarified the physical size of the building, and underlined the need for it to be very flexible, both so that it could accommodate potentially a greater number of staff, and facilitate potential new project teams or departmental structures, given the fluid and dynamic nature of the company’s work. The company was also keen to be seen to be modern, open and transparent. Sustainability was a key word also, not just in terms of meeting the company’s aspiration for a ‘BREEAM Excellent’ building, but the company wanted to be able to show that it had spent money on the right, practical things, that the building would work and that it would reinforce the company’s commitment to sustainability in economic, social and environmental terms, as applied to its whole business. Though championed particularly by the company’s Chief Executive, NRS were in no doubt that sustainability was understood and supported throughout the organisation.

PROCESS

Location - For a company so committed to sustainability and with such a strong history of converting old buildings, the decision to erect a new building on a green field site on the edge of town was not easily made. The location was on two separate bus routes, near a cycle route, and with easy access to the Dundee Ring Road for staff coming from the company’s offices in other parts of Scotland. Having decided on this location, the commitment to making a low-carbon building became even stronger. The BREEAM assessment tool was used to assess the sustainability credentials of the project throughout the design process. Strategic BREEAM workshops were carried out at early stages of the project to steer the design process and to coordinate the design team’s integrated approach to sustainable design.

The proximity of the Dundee Ring Road was to have an important bearing on the design of the building. Being a 70 mph stretch of road, acousticians’ reports said that noise levels would not be acceptable to people working

Main staff area


Boardroom

in a building in which ventilation needs required windows to be opened, so near this road. Having initially thought in terms of a cross-ventilated massive structure, an alternative structure and services strategy had to be evolved. Dynamic energy modelling was carried out to compare the energy consumption for an air tight mechanically ventilated solution with a naturally ventilated solution. The mechanically ventilated solution was found to have lower annual energy consumption when coupled with an earth tube, natural air conditioning system. Earth tubes are a series of buried concrete pipes which pre-heat or cool (depending on the temperature difference between the external air and ground temperature) the building’s incoming fresh air before it reaches the building’s air handling unit. Through dynamic modelling it was predicted that the pre-cooling effect of the earth tubes in the summer would maintain the building’s internal environment within acceptable conditions without the need for mechanical cooling. The use of mechanical ventilation also provides greater occupant comfort, acoustic performance and flexibility for the layout of the building. The final strategy adopted is a mixed mode approach which provides the client with the greatest flexibility.

Orientation - The site available on the Technology Park was too large for one building and Hillcrest agreed on the sub-division of the site with its owner (Scottish Enterprise Tayside), and the development of the remainder of the site by the company Insights. Insights and Hillcrest agreed a shared entrance to the site, and in discussion with Insights, NRS agreed on the Insights building being located at the front of the site, with parking behind, and the Hillcrest building at the top and back of the site, with parking adjacent to the building. This position provided the occupants of the Hillcrest building with good views across the Carse of Gowrie to the Sidlaw hills. While office buildings might normally be expected to present a gable end to the south to avoid over-heating from solar gain, the architects decided after much discussion to orientate the building on an East-West axis to maximise solar gain in winter, knowing that they could provide shade from summer sun by simply incorporating fixed external louvers. Manually operated internal blinds provide occupant control to minimise glare. This orientation would leave a smaller east-west facing face where solar gain or glare through low light would be masked by mechanically operated blinds. This orientation also provided a pocket of green space which enhanced the rear of the building, protected and enclosed by the established tree belt on the site boundary.

Form/plan - As part of their low-carbon aspirations for the building Hillcrest had asked for a timber structure. Engineers and the QS had initially expressed caution on grounds of scale of beams needed to carry required floor plate loads, and cost. Working hand in hand with Buro Happold, the structural engineers Arup, and other members of the design team, solutions were developed collaboratively, as structural decisions were closely related to services decisions (e.g. making building more solid, with less glass in the walls, would have reduced the need for cooling, but reduced day-light, open-ness and views). Through mullions placed at 1800mm centres along north and south sides of the building taking the floor loads down to the ground, a largely timber structure was achieved, with steel used in the form of slender columns in the centre of the floors, bracing for the glass on the east façade, and to a minor extent in the fire

stairs. Although, the timber had to be imported from mainland Europe, much less energy was involved in the use of the timber than if a steel structure had been used.

A simple rectangular plan provides for maximum flexibility, as required by the brief, and with cross-ventilation not required, and structural issues over use of timber resolved, an 18m floor plate was decided on. While losing BREEAM points, by potentially placing workstations too far from window views, this was agreed so as to create flexibility for the siting of workstations to maximise space. The extent of glazing in the building was reckoned not to give any concerns about workstations being far from natural light or from views out, and roof-lights bring light into the centre of the plan. Before the form of the building was finally defined, the architects carried out extensive studies of potential desk configurations in the open plan areas, devising a layout which allowed for new ‘pods’ or ‘splats’ to be added to existing ones without the need to change services, allowing for new work stations to be created or new groupings formed.

Organisation - To satisfy the requirements of a headquarters building, provide a good public image but also meet the company’s objective of dissolving silos between different departments, NRS devised a clear, legible, organisational structure for the building. The ground floor is mostly set aside for shared/visitor use – entrance, café area, kitchen area both for use by staff and to serve board meetings and conferences, conference area, meeting rooms, IT and plant. First floor – cellular offices for Directors, adjacent to large open-plan work area. Mezzanine floor above, further open-plan work area. The entrance and café are open to the full height and depth of the building. Lifts and stairs between floors, toilets and changing rooms are located in a circular drum immediately adjacent to the entrance and at first floor and mezzanine level are connected to the work areas with bridges, providing both connection and open-ness.

A biomass boiler was identified as the main heating source early on. The planning application for the building was submitted in February 2008 and with tenders in by September, work was ready to start on site; but in December 2008, although building warrants had been issued, planning permission was refused after local residents successfully queried the content of PM10 (small particles less than 10µm in diameter) in the emissions from the boiler. The predicted emissions from what was only a 185kW boiler were within the guidance provided to the design team by Environmental Health officials but for some reason the planning committee were anxious.

Despite a positive recommendation from the planning department, concerns from neighbours and local Environmental Health Officers re the levels of particulate matter prompted refusal by the planning committee.

Although Hillcrest did look at abandoning the project and purchasing another building off the peg, they decided to continue their commitment to this project, partly because they had already spent a substantial amount of money on design fees and other costs, and they appealed against the refusal. The appeal was not heard until June 2009, and permission to start on site was given in October 2009, although the final protocols to formally


Open plan working environment


Circulation space on mezzanine

satisfy the planners were not agreed till October 2010, just before the building opened.

The client and design team used this time to bring the design team and contractor together to make sure that the building could be delivered within the £5.3m budget. The contractor had been chosen on the basis of tenders from contractors on Hillcrest’s framework agreement, and was well known to them. Costs which had been based on open specifications in the tender documents were pinpointed to specific suppliers, some costing for risks by the contractor were taken out due to their being able to have this period of working closely with the design team and the contractor eventually agreed a gross maximum price contract.

Hillcrest’s aspiration was not only to create an office building which met the highest sustainability benchmarks but also to use the building to test sustainable design features that could be incorporated into the housing projects they develop. As a result, the appraisal of different sustainable design features not only evaluated the pay back periods and carbon saving potential but also focused on the option of adopting Biomass technology in Hillcrest’s future housing stock.

RESULT

The building sits on a slight rise above its access road. As their obligatory contribution to Percent for Art, Hillcrest commissioned an artist to design a maze of beech hedges which lies on the slope between the corner of the building and the public road. In time this will grow up to further soften the relationship between the building and the road at this point. The aim of increasing biodiversity helped guide the site planting and landscaping of the site, with attention paid to choice of native species and the planting of wildflowers. The top two thirds of the building’s tall 3-storey front is fully glazed, while the ground floor is faced with a wall of stone-filled gabions. The same material is used to clad the 3-storey tower, and together these two stone elements firmly anchor the building to its site. Stones have been omitted in the gabions at the top of the tower so that swifts can nest here. The gabions are filled with stone from the Denstone quarry in Angus, and much of the work was done as part of an apprenticeship initiative run by the contractor, something all the contractors who are part of Hillcrest’s framework agreement are obliged to provide. Ivy and other climbing plants have been planted around the base of the stone drum which in time will climb over the drum and soften its effect.

The biomass boiler is located in a separate building to the west of the main building, to isolate potential fire hazards from the main building, and to provide easy access from the car-park level for the lorry delivering woodchips to the boiler hopper. The building contains the biomass boiler, 2 back-up gas boilers and the filtering equipment and the heat accumulator. In the year between having planning permission refused and the successful appeal, the design team found that technology had moved on and it was possible to install an additional ceramic filter to remove 98% of particulates from the boiler emissions. This removed PM10’s to an infinitesimally small level. The 19.5m chimney coming out of the top of the boiler house was designed to project any unfiltered particulates


Exterior view highlighting sunshades, ventilation system and stone gabions

further away from the immediate area. Though owned by Hillcrest the biomass system is operated and maintained under a 10-year agreement by Angus Biofuels who sell the energy to Hillcrest. The protocols covering the system’s management and maintenance were an important part of the building ultimately receiving full planning permission. The building has also been designed to allow for the future installation of two 15kW wind turbines.

The entrance to the building is at the point where the tower and the north-west corner of the rectangular block meet, and leads into the reception area. Ahead is the café area, open to the full height of the building and with glass walls on two sides. Going left from the entrance runs a wide passage running between 2 meeting rooms and IT department (to the front) and board and conference room (to the rear). These connect across the rear of the building to the kitchen and cafe areas. Beyond locked doors at the end of this floor are access to a gymnasium and changing area, showers, the 9-bay cycle parking area (which includes a charging-point for electric bikes) and the plant room. The cycle garage has its own access from the exterior, and doubles as the staff entrance. The gymnasium was provided as part of Hillcrest’s commitment to ‘Healthy Working Lives’ and as part of their Investors in People accreditation. Initially, a conference/training room was not planned for the building, but when the client requested this, it was found that for little additional cost the plant room could be pushed under the sloping ground further to the west, and the space gained allocated to the training room. Locating the conference room in this HQ building would save money on renting other facilities elsewhere, and on staff travel time.

The first floor of the building has an open plan work area to the rear, and 6 cellular offices for Directors to the front. The 9 metre deep mezzanine floor above is similarly open plan, and very much part of the same space as the open plan first floor. A stair at the west end leads down to an open-sided meeting room suspended between first and mezzanine levels. Tea-points are located at the end of each floor, with small meeting or break-out areas in the corners of each floor. Toilets for each floor (and access to lift and stairs) are reached over the bridge in the tower part of the building.

The primary structure of pre-fabricated glu-laminated (spruce) beams carrying the first floor make an immediate impression from the entrance hall, and further above the beams supporting the mezzanine floor, anchored on the four slender steel columns that are positioned along the length of the building. The secondary structure of floor slabs and roof decks is also of timber – 1800 x 9000 x 75mm cross-laminated timber panels. The structural capabilities of the cross laminated panels enabled very large overhangs (up to 2m) to be formed cheaply and simply.

As the design team was able to convince the planning authorities that the fire protection system in place provided adequate protection for building users in the event of a fire, the timber in the building did not require fire-proofing and is instead finished with a breathable white wax. This not only reduced costs but the resulting whiteness increases the feeling of airy lightness throughout the building.

The four full height steel pillars along the centre of the building visibly bearing the glulam timber and supporting the roof terminate at roof level

Main entrance to building as seen at night


in a light funnel where glazing cut into the roof brings natural light into the centre of the work spaces on the first and mezzanine floors. These light funnels also house a fan and heat exchanger which play an important role in the ventilation and cooling/heating strategy.

Heating/cooling - Air is brought into the building through 5 trunk-shaped ducts rising out of the grass to the back of the building. Low powered fans assist the process. The air is drawn into a ‘labyrinth’ of 600mm concrete pipes that feed into a brick chamber which functions on the same principle as a cave – in summer this will be cooler than the ambient air and in winter warmer, the difference in temperature being about 3°C. At that stage, if required, the air can be heated (by the heat generated by the biomass boiler) if required. The air is then drawn by fans into vents in the wall and the floor in different areas of the building. A computer-programmed BMS system monitors the temperature and air-flow through sensors in 5 separate zones in the building, with the aim of achieving a balance between background temperature and air coming in to the zones, for ventilation purposes. The air rises naturally to the 4 light funnel locations in the roof of the building where heat is extracted by the heat-exchangers and re-circulated to be used to heat the air being drawn from the labyrinth. In two rooms in the building it proved impractical to rely on this system alone to provide cool air and individual air-conditioning units were installed – the IT room where substantial heat is generated by the server and the conference room where it was reckoned that a quicker cooling time was required than could be effected by the fan-assisted natural ventilation.

Heat is provided by the biomass boiler feeding a heat accumulator which then feeds hot water to radiators throughout the building, each fitted with a thermostatic valve. Hot water to tea-points, kitchen, gym shower room and toilets is provided by an array of solar heated evacuated tubes positioned on the roof of the boiler room.

Each window on the North and south façades is fitted with manually operated roller blinds. The glazed West gable is fitted with mechanically operated blinds triggered by a light meter. Lamp units throughout the building are low-energy, with daylight control and occupancy detection to minimise energy consumption. Showers, taps and WC’s are designed for low water-consumption. Rain water is collected from the roof and recycled for use in flushing the toilets. A SUDS is installed externally.

The building envelope exceeds good practice standards for air tightness with a measured air permeability of 3.3m3/ hr/m2. As well as conducting an air tightness test of the completed building, a thermal imaging survey was carried out to ensure the quality of the construction met the design aspirations.

The furniture for the directors’ offices is re-used whilst the furniture for the workspace areas is new, with products and suppliers scrutinised thoroughly for compliance with sustainable principles by Hillcrest’s asset management department. The majority of materials used in the building were Green Guide ‘A’ rated. The whole building was detailed in order to be demountable for re-use or recycling.


Detail of sunshades

IN USE

Since first occupied in January 2011, the building has functioned as designed, with the only issues in terms of operation being the fine-tuning of the heating/ventilation and air-supply systems. For staff previously working in cellular offices, the open-plan nature of the new building has taken some getting used to, but once certain protocols have been taken on board, mainly with respect to volume of talking on telephones, staff appreciate that overall levels of background noise are less than in their previous workplaces. The staff ‘see what they have got is so much better than what they were in’.

The evidence is that users are happy, less stressed and appreciative of the freshness of the air and the non-polluting environment. The office gym is accessible to all Hillcrest Staff, even those not working in the building. The meeting, conference rooms and social/multipurpose spaces are also used by other Hillcrest offices and it is planned to make them accessible, by arrangement, to private groups for functions, events etc., thereby reinforcing links between Hillcrest and the wider community.

Analysis of energy consumption to date indicates that targets have been achieved, with the building achieving a Building Emission Rate of 20.4 kgCO2/m2/year. The design emission rate was 21.7kgCO2/m2/year

KEY LESSONS

The client had an exceptional commitment to sustainability, both in a broad holistic sense and through a detailed focus on particular aspects, as proved by their decision to stick to the biomass heating system despite all the difficulties created in terms of the building receiving planning permission.

This commitment gave confidence to the design team who also took a view of sustainability that went beyond the ‘points system’ of BREEAM (however useful that is as a measuring tool) to a wider commitment that focused on creating a building that would support the wider aims of the company and truly increase the productivity of the company’s employees by providing good quality accommodation that enhanced people’s feelings of wellbeing.

The client’s prior experience of construction (through its core business of building houses) meant that they were a confident and knowledgeable client to whom the design team found it easy to relate. This background also enabled the company to manage the project more efficiently, to maintain good communications with staff representatives, and to bring to the project a close relationship with the contractor, with whom they had worked on other projects. In fact the client, quantity surveyor, contractor and structural engineer had all worked together successfully before and developed a good relationship. The quantity surveyor had worked with the client on some of its housing projects. This meant that the team were, in the client’s words, ‘willing to go the extra mile’ to make things happen. The architects welcomed the partnership approach of the contract where they were able to sit round the table with the contractor and the client’s Project

Manager and resolve details and procedures in a non-confrontational way.

The architects also felt that they developed an excellent synergy with the services engineer Buro Happold in terms of jointly developing solutions that met the client’s aspirations for sustainability.

Although it did not change the way the scheme was designed, the delays caused by the initial refusal of planning permission gave more time for the detailed designs to be fully worked out resulting in the construction phase being completed more smoothly. This time was also used by the client, contractor and design team to ensure that the project could meet all its targets for sustainability criteria while remaining in budget.


Main social and meeting area for staff in the atrium

Detail of cross laminated timber structure

Project Information

Location: 1 Explorer Road, Technology Park, Dundee, DD2 1EGClient: Hillcrest Housing AssociationDate Completed: December 2010Project Value: £5.3mInternal floor area: 2190 m2

Architect: Nicoll Russell StudiosStructural Engineer: Arup ScotlandServices Engineer: Buro Happold LtdQuantity Surveyor: KLM PartnershipSpecialist Consultants: CDM Co-ordinator - Hardies LLPMain Contractor: W H Brown Construction (Dundee) Ltd M&E Contractor : McGill LtdProject Management: Hillcrest Housing AssociationClerk of Works: Hillcrest Housing Association

Awards: Shortlisted for the 2011 RIAS Andrew Doolan Best Building in Scotland Award and awarded a special mention. Best Public/ Commercial Building, Best Client and the ‘Supreme’ Award from the Dundee Institute of Architects, 2011

Image Credit: Andrew Lee

Architecture and Design Scotland

Bakehouse Close, 146 CanongateEdinburgh EH8 8DD

Level 2, The Lighthouse, 11 Mitchell Lane,Glasgow, G1 3NU

T: +44 (0) 845 1 800 642F: +44 (0) 845 1 800 643E: [email protected]

www.ads.org.uk/sust

hillcrest housing association hq. - a&ds

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