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Hot and bothered

The quest to build eco-friendly homes is leaving some tenants sweltering in dangerously overheated properties. Isabel Hardman reports.

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Summertime is not easy if you live in Woods House in south west London. When the sun rises, so does the temperature in the building. And it remains high - even at night. These brand new flats, part of the flashy Grosvenor Waterside development by house builder St James, are so environmentally friendly that they are overheating.

Environmental health surveys carried out in the 267 flats late last year, managed by housing association A2Dominion, found an ‘excess heat hazard’, with temperatures peaking at 37C, nearly 10 degrees higher than the recommended safe temperature for homes. At night, the rooms remain so hot that tenants claim their children are suffering nosebleeds as a result.

To make matters worse, the flats are right next to the railway tracks leading into London’s busy Victoria station. Every time the residents open their windows to let the heat escape, they are deafened by the screeching of trains entering and leaving the station. The noise and heat are so unbearable that one tenant, Robert Adams, is seeking a judicial review against Westminster Council claiming it has housed him in unsuitable conditions.

‘At night it is so hot I can’t sleep except with sleeping pills: I have severe migraines because of the noise and my neighbours tell me their children are suffering,’ says Mr Adams.

How did a new development, completed in January 2009, end up with its tenants complaining of such discomfort? The heat survey, carried out by residential environmental health officers from Westminster Council, found the building’s design was at fault. It has airtight double-glazing to retain warmth and so reduce the amount of extra heating needed. But this means excess heat cannot escape, a problem compounded by an inadequate ventilation system.

Green design hazard

Sustainability experts fear this is not a one-off. They are growing increasingly concerned that the quest for air-tight, heat-retaining homes is leading our new-build stock to become unhealthily hot.

Last week the committee on climate change, which advises the government on sustainability, said Britain needs to adapt its building stock to rising temperatures as global warming advances. Its report, How well prepared is the UK for climate change?, claims many new and existing buildings are vulnerable to overheating.

There is, however, a lack of national guidance on overheating. A report from the Zero Carbon Hub recently recommended updating the SAP (standard assessment procedure, which assesses the energy efficiency of new buildings), to include an overheating test. The report, Carbon compliance for tomorrow’s new homes, says regulations should either require active cooling mechanisms, such as environment-hostile air conditioning, or passive systems, which rely on natural ventilation and the cooling properties of the building’s materials.

Ray Sanderson, head of sustainability at developer Frank Haslam Milan, says: ‘The current SAP model probably needs supplementing with a reliable tool to model overheating as a matter of urgency, which should see lightweight, under-ventilated, over-glazed structures become a thing of the past.’

Ventilation is the key to preventing room temperatures rising above healthy limits. Although the Energy Saving Trust, an independent advisory body, recommends passive forms of ventilation such as stacks which allow the air to escape rather than be pumped out, sometimes mechanical ventilation is necessary.

Material matters

Since starting to build to level four of the code for sustainable homes Frank Haslam Milan has begun installing mechanical cooling to prevent overheating. Mr Sanderson says: ‘Unfortunately this throws up the potential for carbon conflict if this is powered by grid electricity.’ Similarly in some overheating properties, tenants install their own air conditioning to cool the rooms, thereby increasing the carbon emissions of the otherwise eco-friendly development.

Another way to prevent homes becoming heat hazards is to use appropriate materials to build them. The Energy Saving Trust recommends using materials with a high thermal mass, like concrete, which maintain an even temperature by absorbing heat in the daytime and releasing it slowly at night.

Matt Coleman, head of housing at the trust, says: ‘Most builders have been using lightweight materials which do not have the same storage capacity.’

The developer of Woods House admits the ventilation system in the block, a mechanical ventilation and heat recovery system which swaps stale air for fresh, could not, by itself, reduce the temperature in the flats.

In a memo dated 10 November 2009 discussing Woods House, and quoted in Westminster Council’s heat survey, St James claims that residents had ‘incorrectly assumed that the ventilation system would cool their apartments’ and that cooling should be achieved through ‘conventional opening of windows and shading with blinds or curtains’.

The quote from the memo makes no mention of the din from the trains when windows are open, but the survey says noise levels would breach World Heath Organisation limits.

A2Dominion says it is working with residents and St James on the heat problem. St James has covered heating units in the flats to reduce internal heating and installed fans in the corridors, but these will increase the building’s carbon footprint.

It is awaiting a report from the developer, due this week, which will outline other improvements it has made to the flats. The ventilation system has also undergone further tests.

Alan Johnson, an executive director at A2Dominion, says: ‘We regret any inconvenience this may be causing to our residents but we would like to assure them that we are taking the matter very seriously and are taking active steps to address it.

‘We have and will continue to keep residents informed of our progress and hope to resolve the matter soon.’

For Mr Adams, though, these reassurances come too late. His judicial review has been given leave to proceed. Meanwhile he has asked the council to re-house him somewhere quieter and cooler.

He says: ‘Everyone knows about the overheating problems in the flats: but nothing has been done about it. I have lost my patience.’

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