Assembling the assembly

Even before the foundations were poured Scotland's new Parliament building was the most talked about project north of the border. Sitting at the foot of the Royal Mile, Enric Miralles' symbol of democracy has come under intense public scrutiny, often for the wrong reasons. Cost overruns, programme delays and the current Fraser inquiry have all made the news.

Yet behind the headlines this ambitious project has continued apace. A large chunk of the scheme is now complete and ready for handover, while the construction team is preparing for the final push to get the building ready by July. When complete the MSPs will move from their temporary home on the Mound and take up their seats for the first debate. While the public inquiry takes its course, the big question now is what can the 129 MSPs and staff expect from the building that will be the home to the parliament for the next 100 years?

Building brief
Plans for a Scottish Parliament building began following the referendum in September 1997. A brief was drawn up and feasibility studies were carried out on four separate sites around Edinburgh at St Andrews House, Leith, Haymarket and the eventual choice in Holyrood. Rising Catalan architect Enric Miralles was selected in July 1998 through an international design competition and his firm EBMT formed a joint venture with architectural practice RMJM to develop the scheme. RMJM were subsequently appointed as m&e consultants.

In his initial presentation to Donald Dewar, Miralles sketched out his ideas on a pad. One of the strong themes to emerge from this design was that the building should sit within the landscape and reflect its surroundings. In the final scheme a series of sweeping concrete 'fingers' flow from the Assembly building into Holyrood Park and these will form the connection of the building with the adjacent parkland.

By January 1999 Bovis Lend Lease was appointed to provide construction management services, including all trade packages. Pre-construction works commenced in April 1999 with excavation works for the basement level completed in February 2000.

The Scottish Office visited a number of parliament buildings throughout Europe including Dresden, The Hague and Berlin to help compile the brief, which according to Drew Elliot, building services director at RMJM, was very generic both in space terms and environmental aims. "The brief defined a lot of areas that had to have mechanical ventilation and probably cooling. We actually challenged this right from the beginning."

A quick run through of the scheme shows the number of distinct buildings (see figure 1) that make up the 30 000 m² development. The MSP Wing sits at the west end of the site and provides office accommodation for the MSPs and their researchers. Adjacent to this is Queensberry House, a 17th Century grade A listed building, which has been completely refurbished to accommodate the presiding officer and support staff. The debating chamber located on the east side of the site houses a main public space, reception and exhibition area on the ground floor. Above this is the debating chamber, which includes public seating for 225 as well as a further 42 guests and press. Four Tower buildings wrap around the rear of the debating chamber building. The parliament's six committee rooms are located in these, along with offices for support staff and meeting rooms. On the north east corner of the site off Canongate is the media tower, which will be occupied by the Parliament's broadcasting office as well as journalists and external broadcasters. Finally situated next to Queensberry house are the Canongate Buildings, which incorporate a new building as well as the construction of offices behind the existing facade of 58-60 Canongate. Linking all the buildings on the complex is the Garden Foyer, notable for its 12 leaf shaped rooflights, which allow natural light to penetrate into the 35 m deep space.

Early on in the project it was agreed that the scheme would be split into three core sections, the MSP wing, Queensberry House and the Assembly building. This allowed the design team to tender the MSP building and Queensberry House earlier, giving better cost control and enabled the architect to go on and draw up the Assembly building in greater detail before it went out to tender. Significantly, it also allowed the opportunity for the m&e to be split between several sub-contractors.

From the initial brief RMJM set about trying to reduce the number of areas that were specified as mechanically ventilated and cooled. The heavyweight structure of the buildings and the recurring use of exposed concrete finishes (both pre-formed and cast in-situ) helped with this philosophy and also tied in with Miralles' desire to have completely concealed services.

With the exception of high load areas such as the IT rooms (with design loads reaching 1000 W/m²) and kitchens the use of chilled water at the conventional temperatures of 5°C and 11°C has been kept to a minimum. Instead systems were selected which benefited from using chilled water at a higher temperature allowing the local well water to be used for cooling. A total of 20 ahus located in three plant rooms, north, south and east, serve the entire east part of the site (Assembly building). A further plant room on the east side houses 2·4 MW of boiler plant, two condensing and one high efficiency, as well as a 150 kW chp unit. With no large domestic hot water cylinder on site this was sized to meet the 5000 hours operation needed a year. The 80 kW of electrical is subsequently used for running the pumps. Pipe distribution is quite simple and compact, with two-pipe flow, and return being brought out from the boiler house to all the main ventilation plant rooms. In each plant room a set of headers provides lthw to variable temperature, and constant temperature circuits, which serve plant in the vicinity, the Towers, and spaces immediately above.

The MSP wing
The MSP Wing stands six-storeys at its north end stepping down to four at the south and houses offices (each 15 m²) for the 129 MSPs. The construction of the building is a mix of pre-cast and cast in-situ concrete units providing U-values of between 0·225 W/m²K and 0·25 W/m²K for the walls and roof, while the glazing manages a creditable 1·4 W/m²K.

The offices, which feature vaulted concrete ceilings, are arranged as a single bank with a researcher space immediately outside each office and an external corridor beyond this. Initially a mixed-mode strategy was considered. "But what struck us was MSPs don't work a nine to five day and we also felt that the door between the offices and researcher's space would very rarely be closed," says Elliot. Thoughts turned to natural ventilation. For the MSPs offices this was straightforward, two openable windows, one motorised and one manually controlled, are built into the characteristic feature windows (Miralles decided the MSPs needed somewhere to sit and contemplate, he gave them a seat and a floor to rest their feet on, a window, then decided they might need some bookshelves, and simply joined the elements together).

To enable fresh air to be brought into the 'internal' researcher's room the architects came up with a 'punch' window, which penetrates above the external corridor, bringing in natural light and outside air into the researcher's space. Together these will provide cross ventilation, 4 ac/h on a calm day, and passive cooling throughout the day with night-time cooling of the structure during the summer.

RMJM conducted a number of TAS studies to determine the best configuration for heating the offices. The architects were reluctant to put any space heating into the oriel window, but simulations proved this would be too cold. The result is two 750 mm long lthw trench heaters, one installed in the floor of the window with another along the external wall.

The height of the space was a critical factor, both from a planning point of view and to avoid the need for a fire lift, which directly influenced the services distribution. Primary horizontal distribution takes place on the ground floor, with a riser coming up between each pair of MSP offices behind the storage wall. Secondary horizontal distribution then takes place in the shallow raised floor, with each riser serving a pair of offices, a pair of researcher's rooms and every third one serves a section of underfloor heating in the corridor. This is protected by a two-port valve to maintain a maximum temperature of 50°C for the underfloor heating circuit (the trench heaters run at 82°C to compensate for their compact size).

Each office is treated as a single zone and fitted with an individual thermostat and temperature indicator. Any MSP or researcher working late after the heating has shut down can press a button on the thermostat panel that will provide an hour of additional heat in that room. PIRs are also fitted in each office, which will automatically shut down the heating within the space if nobody is detected and similarly if the motorised window is opened when the heating is on. A building user's guide has been drawn up to explain the strategy, in particular to ensure that occupant's use the motorised window first – though no doubt there will be a few rebels.

Indirect lighting in the offices is provided by a fluorescent fitting with an elliptical diffuser built into the top of the oak storage wall, which throws light onto the underside of the vaulted ceiling. This is supplemented by task lights at each of the desks. Floor boxes concealed beneath the oak flooring provide small power and communications, and although the layout of the rooms is fairly standardised their position allows a degree of flexibility.

The Assembly building
The ground floor of the assembly building is the main public area and gives access to the public gallery of the chamber and committee rooms.

Exposed concrete is again a familiar sight throughout the space, which consists of three concrete vaults featuring abstract designs of a saltire cross. A lightwell in each of the vaults allows natural light to penetrate the space in addition to the glazing running along the east and west sides. Ventilation is provided by motorised windows controlled on outside temperature, with a night-time cooling strategy planned to take advantage of the building's considerable thermal mass.

This is also one of the areas in the development to make use of the site's well water cooling – in this case via the underfloor heating and cooling system. Groundwater is extracted from two boreholes sunk 25 m into an underground aquifer - incidentally the site was formerly home to Scottish and Newcastle Breweries who used the potable water for beer production. Water is extracted at between 10°C and 11°C and stored in a 400 m3 buffer tank before being pumped via heat exchangers connected to the cooling water circuits. As well as supplying the public foyer the cooling water supplies the displacement ventilation ahus, chilled beams in the committee rooms and the structural cooling in the press tower. Back-up for this system is provided by one of two 600 kW chillers. The second providing chilled water for the ac units serving the IT rooms and kitchen ventilation plant. Well water also provides grey water for toilet flushing and topping up the water feature ponds throughout the site.

The unique roof structure of the debating chamber, constructed from laminated oak beams and stainless steel joints and ties, enables the space to be kept free of support columns. The floor of the chamber contains seating for the 129 members, which is laid out in a semi-circular fashion. A displacement ventilation system introduces air, cooled using the well water system, through wooden grilles built into the risers of the banked seating – and is heavily attenuated to meet the chamber's NR25 criteria set. This is controlled by carbon dioxide sensors, which throttle back the variable speed fans when there are fewer occupants in the space. Air is extracted at high level through a return path formed by the outer double-glazing and an inner acoustical barrier, back into ducts beneath the floor.

Lighting was a major issue in the debating chamber. Because the parliament was going to be open to the public the designers wanted to maximise natural light entering the space, but at the same time it needed to satisfy broadcasting requirements, which ideally would have meant a black box. The Scottish Energy Systems Group (SESG) based at Strathclyde Universty carried out lighting studies using Radiance software to help select the type and colour of lighting. Around 260, 150 W MBI fittings will be used, clamped to poles dropping down from the roof of the chamber. These will be individually positioned to prevent shadows falling on the faces of the MSPs – a complex process that involves a laser sight to get the precise angles needed.

Sandwiched between the public foyer and the debating chamber is a large but irregular void (formed by the vaulted ceiling of the public entrance) that is used for services containment. Everything from ductwork and pipework to small power and communication cables runs through the space. To help simplify the maintenance strategy there are five colour coded access hatches and from these extends a painted line with a schedule of what can be accessed.

Car park and Queensberry House
Miralles desire for 'invisible' services also extends into the basement car park. The initial scheme had been to extract air though vents built into the structural columns and then via a builder's work duct running up through the MSP Wing to the outside. However design changes meant the car park ventilation plant had to be relocated from the roof to a basement plant room. The upshot of this was that the vertical builder's work duct was now under positive pressure, raising concerns about its integrity over the 100-year design life. To get around this RMJM decided to force fresh air into the car park allowing it to push any carbon monoxide build up out through the entrance and an 80 m2 (2% of the floor area) void running along the west elevation. It was known that the car park wouldn't be used intensively and simulations were carried out on a number of scenarios to see how long it would actually take for fumes to disperse. With five cars leaving simultaneously the time taken for the last traces to be ejected was in the region of two minutes. The car park fans are operated by carbon monoxide sensors and during times of occupancy these will be on tick over ready to ramp up if there is a rise in activity or a fire situation.

Dating from 1681, Queensberry House has undergone a major refurbishment ready for use as office accommodation. Natural ventilation has been retained in the space, which won't be heavily IT intensive. Sitting just 4-5 m from a main road the building had to meet certain security requirements. The existing sash windows were replaced and behind these a blast screen installed. These are effectively heavy oak framed doors, glazed with toughened glass, except for a handful where the lower sections of glass are replaced with mesh. Any occupants wanting to open a window will need to call security who will unlock the blast screen, open the window and then resecure the screen. Maybe not a particularly user-friendly procedure but more desirable than the potential consequences of a bomb blast.

Home straight
The scope of the Scottish Parliament building has changed significantly since the initial concept designs were produced. It has more than doubled in floor area (yet still remains pretty much within the original footprint) and design changes have come thick and fast. For the construction team there is now less than six months to go before the building is due for completion. Commissioning is reportedly going reasonably well and work on landscaping the surrounding gardens has begun. For RMJM one of the project's goals has already been met. Included in the original design brief under the environmental aims was the desire to achieve a 'very good/excellent' BREEAM rating for the scheme. This has been tackled by dividing the project into three parts: the MSP offices, Queensberry House and the Assembly Building, and under the 2002 office rating it has achieved 'excellent' for all three, securing an environmental performance index of 10 for both the MSP Wing and Queensberry House.