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Quay to success

Stride Treglown’s Temple Quay House for the DEFRA in Bristol has the outward appearance of a conventional office building, but is designed to meet rigorous environmental standards I admit that I got lost and had to be talked down on my mobile phone as I frantically skirted Bristol city centre.My guide was Laurence Wood, estates manager at the building I was to visit. His offices on the top floor of the (as was) DETR building in the Temple Meads district of Bristol, gave him a vantage over the main approach roads and he guided me to the rear underground car park.

 

Martin Pease, project architect of Stride Treglown, had been at pains to emphasise the environmental credentials of this building and because I could not make out what the security guard was saying on the entryphone, he had to run downstairs to manually open the gates for me.Was this, I wondered, part of the new energy efficiency regime?

 

Departmental reshuffle The building had only been completed a few weeks prior to the government shake-up in the summer, and when I was there the etched steel nameplate had been hastily covered up with an A4 piece of paper saying DEFRA (Department of the Environment, Food and Rural Affairs).

 

Previously located in Tollgate House, a 17-storey 1960s concrete block with outdated services which was ‘falling apart’, the staff reputedly had to endure the cold winter months in an outdated and unresponsive building for years. There had been an intention to remain there and refurbish 13 floors but, after weighing up the factors such as staff comfort and well-being - as well as the issue of annual service bills - it was agreed to decant to a new venue. ‘There was no way that we could have delivered the environmental benefits within reasonable cost parameters if they’d stayed at Tollgate House, ’ says Pease. For the client, the move must have been warmly welcomed.

 

The project was advertised using an OJEC notice. From 11 received responses three were shortlisted, around a relatively straightforward brief. Criteria included the essential requirements that a new 13,000m 2building be built on a brownfield site (an ex-Temple Meads’ railway yard); that it achieved a BREEAM ‘excellent’ rating; and that it be ‘green’. The client, to a certain extent, allowed the architect to define and justify its compliance.

 

The green pound In order to encourage energy efficiency, the various government departments centred around the old DETR felt that they had to be seen to practice what they preached and operate a successful ISO 14001 policy. ‘We now incorporate everything from the procurement of sustainable resources to monitoring the actual performance of materials and practices through FM [facilities management] audit processes, ’ says Peter Lee, senior estates manager. ‘All paper, for example, is recycled, ’ he says.

 

The energy efficiency remit was a key factor for the architects and they have come up with a flexible and responsive building, ensuring lower running costs, but which does not look like a clichÚd, ‘worthy’ building which expresses its sustainable credentials. In fact, the new building has a distinctly commercial office feel and would fit well into most city-centre development parcels.

 

The architect was guided in this by a client partnership between Castlemore Securities, the developer, and the DETR, the prospective client, which had asked it to provide a ‘green’ building and was willing to be guided by the architect as to what that might entail.Marrying the needs of commercial build costs against the need for real returns on running costs, ‘is the aspect of which we’re most proud’, says Martin Pease, project architect.

 

‘Most people consider that providing a ‘green’ building is going to be expensive, but we have shown that it is possible for market rates.’ Ideas such as photovoltaics had to be dropped, but harvesting rainwater to flush the WCs has been included, with a payback of 20 years at current costs.

 

Even though the building has integral underground car parking, the client has reduced the number of car parking bays for employees. It provides them, instead, with discounted tickets for local public transport. However, with still relatively underdeveloped public transport links to this new site, this has not gone down too well, apparently. A canal terminal is situated alongside the development site for a more romantic trip to work.

 

Bird’s wings The move from the old premises was achieved in three phases - of 430, 180 and 230 staff - with no down time. According to Laurence Wood, the new building has transformed and enlivened the otherwise staid working practices of government departments: ‘We are now much more of a community, ’ he says. ‘I have seen and talked to people that I never realised worked here - who were total strangers - but who have worked for us for years.’

 

The above-ground-level building is a fiveand six-storey triangular office block (wings are named Kite, Hawk and Eagle) with a large fan-shaped atrium. From here, one can access all floors via a cantilevered staircase (see Working Details, pages 36-37) or an interesting free-standing lift whose carriages glide quickly and noiselessly. The facework on the exposed-concrete lift works quite well as a linear feature at the high end of the atrium.

 

The floors are variations on an open-plan theme and benefit from high-specification materials: from windows (and doors onto refreshing balconies) to the desk modules (each one symmetrical - a boon for facilities management), or the movement-sensor fluorescent lights (set in islands to maximise the heat-sink capacity of the concrete soffit).

 

An automatic fire screen has been built in at the seating areas at the far end of the building, opposite the lift lobbies, to ensure compliance with escape route dimensions while keeping the working building open and airy. This maintains views over the atrium for many of the staff in as many areas of informal seating as possible - and the views are impressive.

 

The huge atrium contains the reception desk, capped with a shell-like timber canopy suspended from a mast. Security is controlled from another separate and discreet location to enable the reception area to be simply a focal point for general enquiries.

 

This succeeds in downplaying the impression that you are in the presence of one of the biggest state agencies, with all the paraphernalia of monitoring, security and defence that would otherwise pertain. Similarly, the coffee shop, which spills out into the atrium in an organically formed seating area alongside a second-hand bookstore, is a very relaxed location for taking a break.

 

It is only when you allow yourself to wonder whether schmoozing, networking and the informal contact work more commonly associated with the creative industries, have got any part to play in the bureaucratic workings of DEFRA, that you begin to notice the shift in building symbolism. Pease agrees: ‘The drive was for a friendly and open face to government.’

 

State departments, for me, will always be east European, 17-storey concrete monoliths - but it seems that, to the next generation, they will be accessible, friendly hotel lobbies, in which you will be decaffeinated rather than defenestrated.

 

Energy consumption While the Temple Quay site itself contributed to the BREEAM score - in that it is a previously-contaminated brownfield site and a national transport node with a variety of public transport connections - WSP and architect Stride Treglown decided at the outset that the most important factor in achieving the desired BREEAM rating was that the building should have a low energy consumption. The first task, therefore, was to set an energy target of 120 kWh/m 2/y for the base scheme services, in line with the Econ Guide 19 good practice benchmark for Type 2 (naturally ventilated, open plan building), of 79 kWh/m 2/y for electricity. The biggest challenge was to design a building which met this specification, and which, at the same time, provided a healthy, comfortable working environment.

 

Natural forces The approach that WSP and Stride Treglown decided to take was twofold. First, we ensured that the fabric of the building had a significant contribution to energy conservation. We then designed services that harness all available natural forces, while minimising the building’s negative impact on both the global and local environment.

 

The final building will, for example, have total carbon-dioxide emissions of only 11 kgC/kW/hr, excluding fitting-out works.

 

The resulting four- and five-storey building has been designed around a central atrium which allows the building to make maximum use of natural light and to use mixed-mode ventilation systems, so reducing the dependency on comfort cooling. Temperatures recorded on site during this summer have mirrored the original thermal modelling, with average building temperatures of between 24infinityC and 25infinityC at an ambient temperature of 29infinityC.

 

As a result, the building is naturally ventilated through manual and automated windows and the atrium stack-effect. In hot weather, this system is supplemented by an underfloor air-distribution system that will provide mechanically-cooled air at 19infinityC, supplied from roof mounted air-handling units. The atrium stack-ventilation uses controlled louvres in the roof. In winter, heat from the atrium is recycled by using thermal wheels to indirectly pre-heat the fresh air supply.

 

Adiabatic humidification, which uses less energy than conventional steam humidification, is used during the winter period. The building maximises the use of daylight. Artificial lighting is controlled from a presence and daylight-saving control system incorporated into each light fitting.

 

Night cooling The ventilation system also provides night-time cooling, in conjunction with exposed concrete slabs which form the internal office soffit.The slabs absorb heat by day, which is then purged by cool night-time air, by opening the automated upper windows.

 

Occupants can open and close windows. Perimeter radiators are fitted with individual thermostatic controls. Radiators are run by a lowtemperature hot-water (LTHW ) heating system, while the atrium is heated from a low-temperature underfloor system.

 

To prevent unnecessary overheating, small mechanically-cooled hotspot rooms are provided to house photocopiers, file servers and other heat-producing equipment at each floor.

 

Water Rainwater is collected from the roof of the building in a specific roof tank, for distribution through the building for WC flushing and plant watering.

 

The end result of careful services planning and an eco-friendly design is an efficient, comfortable headquarters with low running costs and - importantly - a BREEAM rating of ‘excellent’, with 74.7 points and an environmental performance index score (EPI) of nine out of a possible10.

 

Structure The building comprises a six-storey reinforced concrete frame with a part-below-ground basement for car parking and a reduced twostorey steelwork roof structure for the building services plant.

 

Construction of the foundations commenced in early 1999 using continuous-flight augured piles,500mm in diameter and up to 20m in length. Some 380 piles were installed, mainly in groups of three and four, although some pile groups contained up to 30 piles.

 

The superstructure is based around a triangular arrangement of offices surrounding a central atrium, with the main frames at 7.5m centres. All offices were 16.5m in breadth with columns centres at 4.5 and 7.0m. Stair cores are located at the apexes of the corners, with five lift shafts contained in two cores in the atrium. Structurally, the building is braced by these shafts. However, the geometrical centre of gravity was vastly different to the mass centre of gravity, which would potentially cause the building to twist under wind loading.

 

The floor slabs have been designed as flat slabs, without the requirement for column heads to overcome shear problem. Each floor, with the exception of the ground, is 250mm thick, the ground being 50mm thicker due to increased loading at this level. At roof level, due to the provision of a false pitched roof to part of the structure, the available room for mechanical plant was very limited. To overcome this, a bespoke reduced-level two-storey steel structure was constructed, hidden from view by a metal screen.

 

The atrium construction differs from the office areas by providing a large glazed roof, supported on slender steel trusses at seventh-floor level. Balcony areas provide access to the lifts, two of which are glass scenic lifts looking into the atrium. These have been constructed using steel beams and columns supporting an in situ concrete slab.

 

One further feature here is the steel staircase, seemingly hanging off the balconies. The perimeter walls are clad with precast concrete panels, imported from Ireland, behind which insulation and dry-lining form the inner skin.

 

Costs

Costs based on the tender sum. Costs per m 2refer to gross internal floor area SUBSTRUCTURE FOUNDATIONS/SLABS £65.84/m 2Excavation on brownfield inner-city site for semibasement, partial steel sheet piling, piled foundations generally, pile caps, lift pits, gas membrane and vent pipework, reinforced concrete basement slab SUPERSTRUCTURE FRAME £37.78/m 2Reinforced concrete columns generally with RC shear walls to lift shafts and stair cores UPPER FLOORS £106.85/m 2RC flat-slab construction forming heat-sink, with enhanced fair-face soffits generally (including roof and balcony slabs) ROOF £38.11/m 2Part single-ply roof membrane on insulated decking finished with gravel or PCC paving flags; part standing seam roofing with structural steel framing ROOFLIGHTS £35.96/m 2Double-glazed solar-treated walk-on atrium roof including structural steel support trusses STAIRCASES £22.31/m 2Precast concrete escape staircases with vinyl sheet finishes and painted mild steel balustrades. Feature steel staircase to atrium with natural slate finishes and stainless steel balustrades EXTERNAL WALLS £63.68/m 2Precast concrete external wall panels (deep reveals) generally with masonry/plasterboard inner skin WINDOWS £77.77/m 2Generally double-glazed timber-strip windows with manual and auto-opening vents; double-glazed solar-treated planar glazing and curtain walling to ‘feature elevations’with structural steel supports EXTERNAL DOORS £4.04/m 2Vehicular gates to car park, steel fire escape doors, auto-control glazed doors to main entrance INTERNAL WALLS AND PARTITIONS £34.98 /m 2Concrete block walls generally to WC cores INTERNAL DOORS £10.53/m 2Hardwood veneered doors in hardwood frames and ironmongery to cores generally INTERNAL FINISHES WALL FINISHES £11.31/m 2Part fair-face concrete, part plastered shear walls;

 

plastered blockwork; emulsion-painted walls generally with full-height ceramic tiling to WC cores FLOOR FINISHES £59.22/m 2Carpeted raised-access floors to offices generally;

 

ceramic tiling to WCs and carpet to core corridors on insulated deep screed; natural slate on insulated deep screed to atrium CEILING FINISHES £39.09/m 2Emulsion-painted fair-face concrete with acoustic baffles to offices; mineral-fibre tile suspended ceilings to WCs and tile corridors, feature timber acoustic ceilings to atrium balconies FITTINGS AND FURNISHINGS FURNITURE £6.01/m 2Window blinds and reception desk SERVICES SANITARY APPLIANCES £4.71/m 2White-glazed ceramic fittings SPACE HEATING/AIR TREATMENT £123.46/m 2Gas-fired LTHW installation; mixed-mode system to offices with natural ventilation via auto-controlled window vents, and underfloor forced ventilation/ cooling; perimeter radiator heating; mechanical supply/extract ventilation to WCs and cores ELECTRICAL SERVICES £119.92/m 2Auto-controlled fluorescent part-uplit luminaires to offices, low-energy compact fluorescent BMScontrolled fittings to WCs and cores; small power to workstations, maintenance sockets, fire alarm system LIFT AND CONVEYOR INSTALLATIONS £23.56/m 2Four passenger lifts (two of which are scenic) with full collective control; one goods lift.

 

BUILDERS’WORK IN CONNECTION £54.15/m 2Builder’s work-holes, fire stopping, laminate-faced WC cubicles and back-panel system; structural steel rooftop plant-access deck and screens; external plant enclosures at ground-floor level PRELIMINARIES AND INSURANCE PRELIMINARIES, OVERHEADS , PROFIT £127.87/m 2EXTERNAL WORKS, LANDSCAPING AND ANCILLARY BUILDINGS £238,681 Nominal 2m wide strip of precast concrete flag and natural York-stone paving to building perimeter, clayware foul and stormwater drainage with precast manholes, utilities contributions and associated builder’s work trenching/ducts Cost summary Cost per m 2Percentage (£) of total SUBSTRUCTURE 65.84 SUPERSTRUCTURE Frame 37.78 3.54 Upper floors 106.85 10.01 Roof 38.11 3.57 Rooflights 35.96 Staircases 22.31 External walls 63.68 5.97 Windows 77.77 7.29 External doors 4.04 0.38 Internal walls and partitions 34.98 3.28 Internal doors 10.53 0.99 Group element total 432.01 40.49 INTERNAL FINISHES Wall finishes 11.31 1.06 Floor finishes 59.22 5.55 Ceiling finishes 39.09 3.66 Group element total 109.62 10.27 FITTINGS AND FURNISHINGS 6.01 0.56 SERVICES Sanitary appliances 4.71 0.44 Space heating/air treatment 123.46 11.57 Electrical services 119.92 11.24 Lift and conveyor installations 23.56 2.21 Builders’work in connection 54.15 5.07 Group element total 325.80 30.53 PRELIMINARIES AND INSURANCE 127.87 11.98 TOTAL 1067.15 100.00 Costs supplied by Frank Wintle, Gleeds TENDER DATE 6 April 1999 START ON SITE DATE 12 May 1999 CONTRACT DURATION 86 weeks GROSS INTERNAL FLOOR AREA 16,347m 2FORM OF CONTRACT AND/OR PROCUREMENT JCT TOTAL COST £17,683,181 (base build only, tenant fit-out excluded) CLIENT PROJECT MANAGER Wakemans AGENT Alder King MAIN CONTRACTOR Wates MAIN SUBCONTRACTORS atrium roof Space Decks;

 

precast concrete cladding Techcrete, M acoustic ceiling baffles Sorba;

 

acoustic atrium panels/atrium screens Kingerlee; windows and curtain walling Velfac;

 

partition systems Unilock; reception desk and canopy Ex Works;

 

carpets Interface; slate and vinyl flooring, tiling Michael Bolton; lift installations Otis;

 

staircase/handrails Cabot Eng; glazed entrance doors City Aluminium;

 

WC cubicles and IPS Shires; lighting Thorn;

 

atrium lighting iGuzzini;

 

furniture supplier (Herman Miller desks) Imperial Office Interiors;

 

roofing Lakesmere CREDITS Castlemore Securities ARCHITECT Stride Treglown: David Marval, Martin Pease, Tony Davies, Katherine Foster, Robert Delius, Tom Futcher, Tim Prior, Antony Davies, Shirley Williams, Tamsin Miller MECHANICAL AND ELECTRICAL ENGINEER WSP STRUCTURAL ENGINEER Clarke Bond QUANTITY SURVEYOR Gleeds

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