If you thought the idea of making a building generate 10% of its own energy was mad, you’d be right. It should be closer to 100%. Here’s how it can be done
Twenty years ago, Britain made its famous dash for gas. As a result, the lion’s share of its electricity is generated by relatively clean gas turbines. However, the government’s last energy white paper indicates that our supply of gas from the North Sea will be exhausted within five years, after which we will have to import our gas through long and fragile pipelines or on tankers from Russia and South America.
At the same time as energy supplies become more uncertain, demand for energy will become greater and electricity generation capacity will become tighter. Much of that increased demand will be caused by carbon emissions and climate change, themselves caused by fossil energy.
The increase in carbon-intensive electric air-conditioning in central Europe is making the most energy-efficient industrialised nations increase their carbon dioxide output. The problem will become particularly hard to live with in urban heat islands: in London, Charing Cross is about 6°C hotter than Heathrow. We had a preview of what a typical British summer will be like by the middle of the century back in August 2003. More than 30,000 people died in Europe from overheating; by the middle of the century, affordable coolth will be as important as warmth for the aged and the underprivileged in the UK.
It is not in the national interest to rely on long-term supplies of fossil fuel. A more workable solution lies in regenerating the urban fabric. We can design new buildings and renovate the ones we have to maximise the benefits of passive heating and cooling using low technology techniques borrowed from the Mediterranean enhanced with the superinsulated heat conservation technologies from Scandinavia. There are no lightweight homes and workspaces in Mediterranean climates. Equally, there are no new buildings without high levels of insulation in northern Europe. What this rules out is the lightweight modern methods of construction being promoted by the ODPM: they are guaranteed to require electrically powered air-conditioning within a few decades.
Solar hot water panels can meet about 40% of the hot water demand of a new home and can supply hot water to run absorption chillers for office buildings. We can design south-facing roofs to be clad in solar electric panels, whether we can afford them today or not – they can easily be fitted as prices drop. Adding flues suitable for wood-burning allows the remainder of our thermal needs to be met by clean-burn wood pellet boilers.
Prices have already dropped to £4000 for a 1.6 kW peak installation using a volume discount scheme. This technology has no maintenance costs and can produce up to 50% of a low-energy home’s electric demand, providing it has energy efficiency appliances. The remaining 50% can be met by building integrated micro wind turbines into the roof, or between buildings.
Sunlight, daylight and wind can also make significant contributions to the energy achievable at residential densities of up to 120 homes per hectare. At higher densities, aerodynamic urbanism becomes more important – see our SkyZED concept.
It is certainly possible to meet 10% of an office’s demand if low pressure drop mechanical ventilation with heat recovery and adiabatic cooling is used. We have designed totally passive office spaces with wind-driven ventilation and heat recovery, allowing photovoltaics and microwind turbines to power appliances.
Anyone unhappy with turbines on hillsides must back urban microgeneration from renewables – or admit that they support nuclear with its dreadful legacy and endorse the continuing war for fossil fuel
The output of small, integrated wind turbines can be significantly increased by careful design of the building form. Give us a chance to design the next Swiss Re and we’ll show how a holistic approach can create great architecture and achieve the 60% CO2 reductions needed to meet Blair’s 2050 target.
If we employ these distributed generation technologies, there is no need to invest in wasteful centralised power stations, and the limited stocks of national green grid electricity can be used to subsidise our heritage buildings, which cannot easily accommodate renewable harvesting technologies.
The trouble is that no big industry player has declared an interest in promoting distributed generation. They prefer to invest in large-scale centralised power stations that are easy to control and fund – and make money for large companies and political lobbyists.
The common excuse is that small-scale renewables are too expensive – and yet this is only true because they are patronised by a handful of enthusiasts who cannot achieve economies of scale. About £5bn was spent in Iraq last year, whereas £2.5m was used to fund renewable technologies through the Clearskies grant. John Prescott wants to build 3.6 million homes by 2016 as part of the sustainable communities programme; this could provide the engine that creates the economies of scale to make our homes and workspaces the power stations of the future.
It only takes 5000 of the additional 160,000 homes planned each year to be built to the ZEDstandards specification, on English Partnerships land, for there to be no additional cost on new-build. At the same time, it would drop the prices for the same renewable technologies to be used on our historic building stock without resorting to coercive legislation.
Anyone unhappy with turbines on hillsides must back urban microgeneration from renewables – or admit that they support nuclear with its dreadful legacy and endorse the continuing war for fossil fuel
Bill Dunster is an architect and founder of Bill Dunster Architects
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