Making Reading Cool Again
At first, precast concrete might appear at odds with ‘green design’ principles, but an award-winning library in Brighton successfully demonstrates how energy efficiency can be achieved using a unique, hollowcore concrete system to heat, cool and ventilate the building.
In October this year, the Energy Performance of Buildings Directive will ensure that all public buildings over 1,000 sq metres are required to prominently display an A-G rated energy efficiency certificate. Ahead of this legislative change, Brighton and Hove City Council’s Jubilee Library is one civic amenity which has already won plaudits for its outstanding design and energy performance.
Central to the building services strategy, the cleverly-built, stylish library uses TermoDeck, a fan-assisted heating, cooling and ventilation system from Tarmac, which exploits the high thermal mass of structural, hollowcore concrete slabs to control internal temperatures and distribute warmed or cooled fresh air throughout the building.
The Jubilee library’s striking three-storey design includes offices, reading rooms, meeting rooms and staff accommodation situated either side of a central double-height atrium. It is one of the UK’s most energy efficient public buildings.
A concrete hollowcore solution
Specified by Fulcrum Consulting, a leading building services consultancy, TermoDeck has helped to create a ‘thermal sink’, which acts as a vital part of the building’s passive heating, cooling and ventilation system. Precast hollowcore slabs from Tarmac Topfloor with a depth of 260mm were incorporated into the office ceilings on either side of the central atrium.
Summer cooling, winter warming
David Selvage, senior associate at Fulcrum Consulting, explains: “In summer, cool night air is pumped through the hollowcore slabs to cool temperatures inside the building. During the day, TermoDeck helps temperatures to stay at comfortable levels because of this stored ‘coolth’ in the concrete and the way that the slabs behave as passive heat exchange elements.
“Critically, in high thermal mass structures, external temperature variations are not reproduced as rapidly inside the building, because the maximum heat level reached during the day is delayed by the thermal mass of the concrete and counterbalanced by the cool of the night. The peak temperature is delayed later in the day compared to a more light weight structure” says David.
Once installed, the TermoDeck system requires minimal maintenance, made easier by the fact that all moving parts are contained within the plant rooms. The system’s innovative design also helps the library to keep energy usage to a minimum and further reduce carbon emissions.
An alternative to air conditioning By exploiting the high thermal mass of concrete, TermoDeck negates the need for potentially energy-intensive heating and ventilation solutions like air-conditioning. From an end-user perspective, the mechanical plant required by TermoDeck to heat and cool the library is significantly smaller than in air-conditioned buildings, and is usually contained within one plant room.
Air extraction
In addition to TermoDeck, the Jubilee Library’s uses a passive ventilation system for the central area. This was to achieve excellent reading conditions as enters daylight through a transparent roof. Three wind towers sited on the building’s roof extract warm air from this central area out of the building. In winter, air is extracted mechanically and useful heat from equipment, occupants and lights recovered. This reclaimed heat contributes towards heating the building.
To further reduce energy consumption, artificial lighting adjusts itself to ambient light conditions and automatically dims when the library enjoys bright daylight. Slatted louvres positioned behind a south-facing glass wall provide shade from the sun in summer, while allowing warmth from low-angle rays during winter.
David Selvage continues: “There are two air handling heat recovery units with 50Kw gas heater batteries. This equates to around 20 percent of a typical 600Kw boiler installation that would normally be utilised for a building of this size. In energy terms, the heating system now uses around 20Kw hours per sq metre per year, which is an exceptionally efficient energy performance.”
Excellent Value for Money
What is remarkable is that at £8.1 million, the Brighton Jubilee Library was a shining example that good design does not have to cost more money. The Mechanical and Electrical services represented only 16 per cent of the building cost and the active thermal mass system only one per cent of construction costs.
As a low energy public building, the Jubilee Library demonstrates that well- designed, concrete cored buildings can meet the need to create more energy-efficient buildings that can cope with potential climate change. High thermal mass systems like TermoDeck not only reduce the need for energy-intensive air conditioning systems, but can also help to minimise energy consumption and provide comfortable environments for library staff and visitors both now and into the future.
Countdown to legislative change
In October this year, the introduction of the European Performance of Buildings Directive (EPBD), will require all new build public buildings over 1,000 square metres to permanently display an A-G rated energy efficiency certificate. The implications for building design will be far-reaching and proven renewable technologies will finally move from ‘best practice’ sites to the mainstream. As well as proven onsite renewable technologies, significant energy efficiency gains can also be achieved by ensuring that the fabric of new buildings is thermally efficient. High thermal mass systems like TermoDeck are one such way to meet this challenge, delivering carbon savings whilst providing comfortable internal environments.
4 December 2007
