The sky's the limit

03/10/2008

The city may be famed for its frequent drizzle, but 10 Manchester tower blocks are to harness the sun’s energy in a £500,000 scheme to make them greener.

When the photovoltaic panels are fitted to the 1960s high rises over the coming weeks, the energy generated will power their communal lighting and lifts. Any surplus, it is hoped, will be sold back to the national grid, with the profit ploughed into other efficiency schemes run by the landlord, arm’s-length management organisation Northwards Housing.

The ALMO’s regeneration manager, Greig Lees, says: ‘The residents of these blocks are mainly elderly and fuel poverty is a real problem. We wanted to bring down their bills and cut carbon emissions from our highrise flats, and PV had great potential.’

By investing £250,000 into the project — matched by the government- funded low carbon building programme — Northwards is one of several social landlords working to make tower blocks more eco-friendly. According to the 2005 English House Condition Survey, there are 305,000 high-rise dwellings in England alone — including 185,000 owned by local authorities or housing associations.

After falling out of fashion in the 1970s, land pressure has put tower blocks back on the agenda — with high-rises being built in cities and older ones refurbished under the decent homes drive.

There are practical and political reasons for improvement. Energy costs are spiralling and, amid fears over global warming, the UK government has pledged to cut carbon emissions by 60 per cent by 2050. It’s well known that domestic use is blamed for 27 per cent of carbon dioxide emissions, and multi-storeys have traditionally been the worst offenders.

Toby Balson, senior consultant with the housing futures team at the Building Research Establishment, explains: ‘The 1960s-style high rises tend to have a huge carbon footprint. Most have walls that are a single layer of brick, and no wall or roof insulation. They can be very draughty and so lose warm air very quickly. For safety reasons, few are supplied with gas so they rely on electricity, which is three times more carbon intensive.’

Old and new blocks pose different challenges when it comes to getting greener. Since April, new social housing must meet level 3 or above on the communities and local government department’s code for sustainable homes — 25 per cent more efficient than the standard building requirements.

Although there are not yet such targets for emissions from existing housing, the Chartered Institute of Housing would like to see binding targets brought in for old stock. In the meantime, housing providers are increasingly using new technologies — and grant funding — to make high rises more efficient.

New towers now incorporate basic improvements that make them greener than their predecessors. Walls and roofs are well insulated, windows double-glazed and doors fitted properly to maximise air-tightness within the building.

Malaysian architect Ken Yeang — who designed a residential block for London’s Elephant and Castle revamp, which is now on hold — took these principles further with his designs for climatically responsive towers, with natural ventilation, passive cooling systems and energy-saving claddings (see box: rising to the challenge).

Bill Dunster — the British architect behind Peabody Trust’s Bedzed urban village — is also at the forefront. His 2004 prototype, Skyzed, introduces other green solutions to high-rise design. Water would be reclaimed, and a combination of wind and PV components mounted within the cladding would meet its electricity needs. Smart insulation would protect against heat gain in summer and heat loss in winter, improving efficiency.

Today, energy production is increasingly being integrated into the building of tower blocks. Windowless areas of south-facing walls can be clad in solar tiles for double the price of regular cladding. Modern heating systems are more efficient — replacing storage models with air source heat pumps and solar thermal.

More ambitious are combined heat and power generators, which produce heat, hot water and electricity. The Stratford Eye, a 19-storey development of offices and flats being developed by housing association London and Quadrant, is being fitted with this equipment — which is expected to cut its carbon dioxide emissions by up to 93 tonnes a year.

Over the coming years, even more efficient forms of communal heating — ideal for high-density buildings such as blocks of flats — are likely to come on to the market, according to experts at BRE. In theory at least, many of these approaches could be adapted for refurbishments of existing high rises. But making a significant difference to older tower blocks can prove prohibitively expensive. The result is that cash-strapped landlords may take a piecemeal approach.

For those that wish to become greener, £50 million in grants has been allocated to pay up to half the cost of micro-generation projects such as PV, wind turbines and ground source heat pumps, under phase two of the LCBP, managed by BRE. The scheme, which does not cover standard energy efficiency measures, is expected to end next year.

This and previous funding streams have allowed a number of existing social housing tower blocks to become more eco-friendly. Last year another ALMO, Solihull Community Housing, installed PV on seven high rises in an initiative so successful that it is being extended to a further 30.

Over the next two years, all but five SCH blocks which are earmarked for demolition will benefit from solar energy in the ambitious £960,000 plan. Half the cost is being met by the LCBP, with SCH and Solihull Council each contributing 25 per cent.

The motivation, explains SCH energy conservation officer Robin Dunlevy, is the effect of spiralling fuel bills on a community in which 70 per cent claim benefits. ‘Energy prices have rocketed this year, and we can only see them rising higher. For this reason it made sense to get all our blocks done,’ he says. ‘Also, we’re getting £960,000 worth of technology for £240,000. If now’s not the right moment, then when would be?’

Wind power

Others are finding different ways to adapt their existing tower blocks. Bradford Community Housing Trust is working on 17 high rises — putting in insulating external walls and roofs and fitting low-energy lights in communal areas to boost efficiency.

Wind power is also cutting bills, after five blocks were fitted with roof-top turbines. Wind is also being harnessed by London’s Homes for Islington, which this summer fitted a 12 metre turbine to an 18-storey tower, Kestrel House, as part of a council pledge to install four in the borough.

The energy produced will power the lifts, lights, water pumps, CCTV and concierge area, saving an estimated 112 tonnes of carbon dioxide over 20 years.

But despite a recent refurbishment, no improvements have been made to the thermal performance of the walls.

Such technology is far from perfect. The small roof spaces of many tower blocks limit their solar capacity and green energy potential. Wind power, in particular, can be hit and miss, even on the roof of a high-rise tower where wind speeds are faster than on the ground. If other buildings are clustered nearby, gusts can be turbulent and inconsistent — the opposite of what is needed to generate power.

‘This is one technology that should be approached with caution,’ warns Mr Balson. ‘Before fitting a turbine, a detailed survey should be carried out for about a year, to check the wind patterns at that exact spot.’

And while micro-generation can make a dent in communal energy bills, BRE cautions against jumping to renewables without some basic improvement to old tower blocks.

‘Making these kinds of buildings greener is complex and expensive so it can be tempting for registered social landlords to go for micro-generation first of all, thinking it’s going to solve all their problems,’ says Mr Balson.

‘Improving heating systems involves laying pipe work around the building, while external cladding involves putting scaffolding up, which costs a lot. Insulating internally reduces space slightly in the flats and then there’s the question of what to do with residents while work is being carried out.

‘The problem is that if you haven’t sorted out the fabric of the building first — the walls, floor, roof, windows and doors — the value of renewable energy is severely diminished.’