Introduction

The GlaxoSmithKline (GSK) Carbon Neutral Laboratory for Sustainable Chemistry was designed as an exemplar of sustainability in design, construction and choice of materials, and one which would be carbon neutral over its 25 year lifetime. It has achieved these aims since completion, gaining the highest levels of sustainable building certification – BREEAM Outstanding and LEED Platinum awards. To achieve such high sustainability credentials – a 70 per cent reduction in embodied carbon compared to conventional buildings – the architect, Fairhursts Design Group, has used timber throughout, for structure, walls, floors and cladding.

As a building type the laboratory is also innovative, aiming to be a catalyst for new industry collaborations and to focus on the highest ‘clean and green’ standards to minimise environmental impact and ensure that new chemistry developments will be energy resource-efficient and sustainable. It will also act as a regional hub for chemistry education, giving local schools and colleges access to working laboratories and technical support.

The laboratory stands prominently in Nottingham University’s new innovation park and its sustainability aesthetic is immediately clear; four timber-clad ventilation towers stand along the ridge of the pitched roof, which is lined with photovoltaic panels on the south side and with a green roof system on the north side. The green roof extends as a continuous slope on each side of the main entrance, creating a sheltered courtyard. The main entrance leads through a circulation space which opens into the ‘winter garden’. This light-filled, double-height space, running the length of the south façade, is the social and circulation hub of the laboratory. An elegant timber staircase rises to an open mezzanine balcony which gives access to the first floor laboratories. The glulam and CLT structures to the mezzanine and south wall are exposed, creating a warm, non-clinical ambiance, with seating and tables below the mezzanine where colleagues and visitors can sit and talk.

There are five teaching and research laboratories on the first floor, write-up space for about 100 researchers, together with dedicated instrument rooms, a Nuclear Magnetic Resonance (NMR) suite, a teaching laboratory for advanced undergraduate classes, and space for a range of outreach activities for schools. Unlike a traditional ‘territorial’ chemistry laboratory, the spaces
are designed to be used as a research ‘hotel’, with sharing of facilities such as fume cupboards. The laboratory environment has been opened up, with clear views to aid collaboration and with the timber structure and services exposed to view.

Sustainability and design

The building form originated in the need for highly serviced laboratory spaces which could be naturally ventilated, resulting in a deep plan and a pitched roof with large rooflights to draw natural light into the internal spaces of the laboratories, and high ceilings for natural ventilation. The relatively shallow roof pitch was ideal for the photovoltaic array on the south side and the green roof system on the north, which also assists rainwater attenuation. To control the internal environment, the roof has deep overhangs and windows are inset into the façade. The walls are clad with a rainscreen of western red cedar boards and single-fired terracotta panels, both chosen for their low-embodied energy.

The structure consists of a braced glulam timber frame of beams and columns with cross-laminated timber (CLT) forming the floors, structural walls and roof deck. This type of hybrid design allows the structure to be flexible when it comes to meeting any future building changes. The use of prefabricated timber components reduced construction time and allowed project planning to become less dependent on weather and more predictable.

The CLT and glulam components are manufactured from PEFC- and FSC-certified sourced spruce. The timber frame contains almost 1,600 tonnes of carbon extracted from the atmosphere through the process of sequestration and tree growth and should make the building carbon neutral over its 25 year life.

The selection of CLT for the floor structure was one of the earliest decisions by the architect; it was the ideal material for the large structural bays on the first floor and it also met the stringent vibration criteria required for the laboratories. The CLT floors are supported by the glulam structural frame and CLT panels are also used for the roof deck, the structural walls and a number of internal divisions. The large format of the CLT elements allowed the internal layout to be flexible; smaller cellular spaces were created by lightweight partitions, giving the opportunity for future adaptability. All service penetrations through the CLT were pre-planned and factory cut.

The use of CLT for structural walls offered other advantages: exposed as a surface finish, it is a material which is warm, subtly varied in tone colour and uniquely attractive. It also cuts out the need for wall linings and plastering, with resultant saving in cost and gains in carbon benefit.

The glulam frame is mostly exposed internally. A series of 500 x 500mm glulam columns, each weighing up to 1.5 tonnes, extend through the height of the building and support 960 mm deep glulam beams on a typical 10.35 x 6.6 metre structural grid.

To help achieve the building’s sustainability requirements, the quantity of steel in the building was reduced by the use of traditional timber to timber connections. The steel dowel fixings were capped with oak plugs, which provides an attractive finish, acts as fire protection to the steel dowels behind and accommodates construction tolerances.

The ventilation towers

Four large prefabricated ventilation towers on the ridge of the roof provide natural ventilation to the interior. The building shape creates wind pressure at the ridge, allowing the four towers to direct incoming air into the laboratories and, via heat exchangers, to provide heat recovery. All the laboratories have fume cupboards. In a conventional laboratory fans are used to provide mechanical fume extraction to the fume cupboards, but here they are vented through the towers, reducing reliance on fans.

The four towers stand at a 45 degree angle and cantilever from the base, rising almost 10 metres above the ridge. Engenuiti, the structural engineer, working with B&K Structures, developed the design of the towers so that they could be assembled at ground level and then craned into position as a single self-stable piece, eliminating the need to work at height. The towers were prefabricated from glulam and CLT and were fitted out with services before being craned into place, each weighing about 11 tonnes. They are clad with western red cedar boards to match the external walls. Their prefabrication and erection were an important element in the sequence of construction and helped the team to meet the programme.

Other sustainability factors

The laboratory is heated by a 125kWe biofuel combined heat and power (CHP) system which exports excess heat to adjacent buildings on the campus. It is supplemented by a 230.9kWp array of photovoltaics on the south pitch of the roof. LED lighting has been fitted throughout at an average of 5.4 Watts/sq.m. It is estimated that the building will save more than 60 per cent of power and will use just 15 per cent of the heat needed for a more traditional building design. Excess energy created by the building (some 40MWh) will provide enough carbon credits over 25 years to offset the construction phase.

Awards

2016 Structural Timber Awards – Client of the Year

2017 Building magazine – Sustainability Project of the Year

2018 RIBA Regional Award

Source: TRADA UK