Funding for the refurbishment of the British Library of Political and Economic Sciences was dependent on demonstrating an environmentally conscious design. This is how it was achieved.
TThe British Library of Political and Economic Sciences is located in the Lionel Robbins building at the London School of Economics (LSE), providing an information resource to students and staff as well as outside visitors. In 1994 Foster and Partners was commissioned to produce a feasibility study for redeveloping the building, as it was desperately in need of upgrading.

In 1997 Fosters was asked to revise the scheme to implement cost-cutting measures, without compromising the design principles established in the initial study. The project was given the go-ahead in July 1998 and further enhancements were made to the design as the project proceeded. Work began in October 1999 and the building was completed in March 2001. Oscar Faber was appointed to design the mechanical and electrical services, and also the architectural lighting, building acoustics, IT and fire consultancy. Works included advanced cfd modelling and life cycle costing.

The original library had been created from two buildings belonging to W H Smith, one was used as offices and the other as a warehouse. As a library it suffered from a number of problems, including wide variations in internal temperature and humidity (18-31°C, 30-80% rh), poor ventilation and a generally oppressive ambience. As the library usage also encompassed IT there were also problems with glare on vdt screens, due to the lack of daylight controls and inappropriate artificial lighting.

Foster and Partners decided to use the existing lightwell to create a new central atrium penetrating through to the basement, providing daylight deep into the heart of the building. New centralised vertical circulation was also provided, in the form of a stepped helical ramp rising to all floors, as well as a pair of glass lifts. These are believed to be the first motor room-less feature lifts installed in the UK, with the motors mounted on top of the cars.

The new 20 000 m2 building also provides accommodation for the school's research centres. There are four in total, each occupying approximately two thirds of the fourth floor and a new fifth floor that was built on the existing roof level.

While the facades were retained, the interior of the original building was stripped back to the structure and rebuilt. It was also necessary to upgrade the windows to ensure an airtight building envelope with reduced air infiltration. This combination of making the building airtight and installing double glazing is believed to have saved around £14 000 a year on heating costs.

Introducing energy saving measures was critical to obtaining funding, which was provided jointly by the Heritage Lottery Fund, the Higher Education Funding Council for England and the Economic and Social Science Council.

The combination of a central atrium, good floor to ceiling heights and an exposed slab, turned Oscar Faber's minds to natural ventilation. "This project became an opportunity to explore a natural driving force to ventilate these spaces," explains Mike Burton of Oscar Faber.

Astride the atrium is a partially glazed 'baby' dome, similar to the one used on the Reichstag building in Berlin. By fitting the dome with opening windows, it was possible to use the atrium to create a stack effect and draw fresh air through the building.

"To achieve this we had to ensure good openings at the perimeter of the building so we used old style windows," says Burton. "The windows have been designed to open and allow occupants to control their local environment. In addition, the windows have motorised top opening lights to allow night time ventilation."

The motorised windows are linked to a self-learning bems program, so it 'learns' that after a period of time at the same temperature it must open the windows. "To reassure ourselves that we would have the correct temperatures and velocities in all of the areas we did extensive 2D and 3D cfd modelling," recalls Burton. "This was important as we were working with extremely low pressures.

We also had to look at the effects of furniture blocking air paths. Since the library has opened we have seen that with high heat gains, having the windows open combined with the atrium stack produces very comfortable conditions."

Modelling was used to assess the need for humidity control and it was established that unless the external temperature fell below zero the relative humidity would remain above 30%. During times of extreme cold an override system adjusts temperatures to compensate.

While the natural ventilation maintains comfort conditions for most of the building there were some areas requiring special consideration. "The double height reading area on the lower ground floor would have been tricky to ventilate naturally as it's below ground level. We did detailed cfd modelling to ensure the mechanical ventilation didn't affect the stack by creating too much pressure at the bottom.

"The fourth floor reading area also needed special attention because it has no windows. We had to mechanically ventilate this area but found that we couldn't introduce cooling as the cold air would fall down the balcony and affect the draw of the stack," Burton explains.

Within areas not open onto the atrium (for security or acoustics), variable speed fans are used to pull air through the areas. The fans are operated on presence detection and temperature so they only work when the room is occupied and the temperature is too high. The research area on the fifth floor, which is separated from the atrium by a glazed curtain wall to reduce noise, is treated in a similar way. The glass for the curtain walling is solar controlled to reduce solar heat gains.

Combining old and new
Where possible, the existing perimeter heating and associated pipework risers have been retained and modified to suit the new floor plan, with new heating being provided to the fourth and fifth floors. Heating systems are supplied with low temperature hot water from three new low NOx/SOx gas-fired boilers located on the roof. The same sensors used to control ventilation are also used to control heating.

Hot water is provided through point-of-use electric water heaters to avoid the need for central storage and distribution.

Through the installation of high efficiency heating plant and the use of zone control, the library is expected to save £8 000 per year on heating costs. Waterless urinals have been installed throughout the development making huge savings on water consumption.

Smoking out the problem
Another major consideration in building design was smoke ventilation. Using modelling again, Oscar Faber was able to persuade the building control officer that smoke ventilation could be achieved naturally. The two fire fighting lifts have a mains back-up supply. Most of the smoke detectors in the building are optical but where these are not suitable heat detectors have been installed. Detectors in concealed spaces are fitted with remote indicators.

An aspirator system is used to provide cover within the spiral stair area, using the steelwork of the lift shaft to allow the 25 mm aspirator pipework to run up and down the atrium. Sampling points are provided at each floor level and additional smoke detectors are installed at the top of the atrium.

The fire alarm system is radio-based, so there was no wiring required, which helped in finishing the building on time. "Once the building structures had been exposed there was more remedial work required than had been anticipated, so this compressed the m&e programme. The quick installation and commissioning of the fire alarm system saved time," Burton recalls.

This is a fully addressable, monitored system, mains powered with battery back-up. The batteries provide standby power for 72 hours with the panel in quiescent state, after which time there is enough power remaining to work the electronic sounders for a further 30 minutes.

Some light reading
In keeping with the design of the other services, the lighting system has energy efficiency at its core – making maximum use of daylight backed by daylight linking and presence detection in selected areas. This combination provides around £24 000 a year savings on lighting costs.

Within the book stacks fluorescent fittings are mounted on the soffits, with a perforated plate to provide uplighting. Most lighting is direct however, because of the need to provide high vertical illuminance at the base of the stacks (150 lux vertical, 300 lux general).

Lighting of the helical ramp was a challenge because of limited opportunities for mounting luminaires. It was overcome by placing downlighters on the edge of the ramp, so they illuminate the level below. Because of the lack of space, the transformers have been located remotely and these are designed to under-run the lamps at 11·8 V to increase lamp life.

The lighting control is operated separately from the bems, using a dedicated lighting control system that can be re-programmed to reconfigure the lighting. In public areas the lighting is fully automatic and in staff areas it is manual.

Three existing low voltage electrical supplies, with an availability of 500 kVA, have been upgraded to cater for the building's future requirements. Primary distribution of electrical supplies is from the lv switchboards, generally using radially fed multicore xlpe/swa/lsf cables. The cables terminate in busbar risers and mechanical plant motor control cabinets. Cabling to the fire alarm panel and fire fighting lifts comprises multicore micc cabling.

A busbar riser is provided within each of the three stair cores and at each floor level miniature circuit breaker distribution boards have been installed to provide power for local lighting and small power circuits.

Quiet please
While most of the library operates a traditional reading room environment there are certain areas, such as the main entrance and the issue desk, where noise levels can be a problem.

"To control these problem areas we introduced acoustically absorbing finishes to the soffit, thus minimising unwanted noise transmission to the lower ground areas and up to the atrium," explains Burton. "In addition, the balustrade to the entrance area is designed to discourage people from leaning over and therefore reduces the likelihood of disturbance to users on the lower ground floor.

"Because of the room size at the lower ground/ground level, individual conversations and speech are unintelligible beyond a few metres away. This is important because much of the disturbance caused by noise and particularly speech is a direct result of the information content, as opposed to the absolute noise level," he continues.

"It was surprising how much of an effect the books had on the acoustic absorption, as well as the thermal mass," adds Burton. "It made a huge difference to the calculations and to the internal conditions."

Information technology
In designing the IT system is was necessary to cater for a future increase in the use of computer workstations, as well as catering for current technological requirements. An interface was installed between the existing server room at nearby St Clements House, using existing ducts, and a new server room has been built on the lower ground floor.

Fibre optic cables from this point radiate out to wiring cabinets located on each floor. Two wiring cabinets are provided for each floor, with each cabinet incorporating a patch panel and hub. In total, over 800 data points are provided for library users with approximately an additional 500 points for staff.

Highs and lows
The design of the new British Library of Political and Economic Sciences demonstrates that the environmental needs of a high tech IT-based library can be met by the use of relatively low-tech building services.

The combination of natural ventilation and good daylighting design have reduced the environmental impact of the building considerably, and with the help of appropriate control strategies the energy consumption of other services has been kept to a minimum.

Engineering data

External design conditions
Winter
-3°C db, 100% rh (fabric heating)
-8°C db, 100% rh (air heating systems only)

Summer
29°C db, 20°C wb for areas mechanically cooled.
35°C db for heat rejection plant

Internal design conditions
Rare books area
17°C 55-60% rh

Reading room
21°C 50-55% rh

Heating and ventilation only
Entrance/reception 16°C min with local heating to reception desk

Cellular offices 20°C min
Staircases and corridors 16°C min
Toilets 18°C min
Stores 15°C min
Plantrooms 10°C min (where internal)
Lift motor rooms 10°C min

Mechanical cooling, heating and ventilation
IT training 20°C min, 24°C max
Server room 20°C min, 24°C max
Meeting/conference rooms 20°C min, 24°C max

Mechanical ventilation
Fresh air 12 l/s per person
Toilets 8-10 air changes per hour
BS5454 areas six air changes per hour, 10% fresh air
Print shop local extract
4th floor reading area 12 l/s per person

Internal gains
Small power 15 W/m2
Lighting 15 W/m2
Server room 24 kW

Filtration standards
Air handling plant generally EU6 BS5454 areas activated carbon filters, 80% efficiency
Local cooling units EU3

Internal noise criteria (for selection of mechanical services)
General library areas NR35
Toilets NR40
Research areas NR35
Server room NR55
Archive rare books NR40
Archive reading areas NR30

External noise criteria (for the selection of mechanical services)
Plant noise emissions not to exceed the following levels when measured at 1m from any plant intakes or discharges at ground level or 1m from the perimeter of the roof. 53 dB(A) day time (0700 until 2200)
47dB(A) night time (2200 until 0700)

Illumination levels
Archive/rare books 50 lux with UV control to BS5454
Archive reading 350 lux with UV control
Offices 350-500 lux
Entrance 200 lux generally plus exhibition lighting
Circulation areas 150 lux
Plant rooms/stores 150 lux
Toilets 150-200 lux
Server rooms 500 lux
Training rooms 350-500 lux
Compact shelving and book stack areas 300 lux general, 150 lux on vertical plant on shelving
Open plan study 300 lux, Ct 2/3 suitable for vdt usage
Lower ground floor background ambient lighting with local task lighting provided as part of furniture

Electrical loadings
General library areas, small power and IT 20W/m2 (peak value)
Lighting 20W/m2
Server room 30 kW

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