Sunnier view of saving energy will mean low-carbon homes

Published on Sunday 12 October 2008 21:34

Looking back from 2050, SUSAN ROAF explains how solar energy helped cut emissions of greenhouse gases by 80 per cent

AT THE turn of the 21st century buildings were the major contributor to climate change. Buildings used about 50 per cent of all energy in developed economies and produced over half of all their greenhouse gas emissions. Yet year on year fashionable buildings became more energy profligate. The more “modern” they were, and the taller and the more highly glazed they were, the more greenhouse gases they produced.

Conventional wisdom held on to the bitter end in the conservative property markets because there were so many vested interests involved. People knew what they knew how to do and had made sure over the years that they profited from it. For instance the lighting profession had developed standards that required excessive lighting.

Some experts hypothesised that it was too noisy and polluted in cities to open windows, despite the fact that others had long been telling occupants that the air quality in air-conditioned buildings caused increased incidences of sick building syndrome and that air quality was better outside than in. It could be argued that in some cases the “standards” that were ostensibly developed to protect the interests of the general public often resulted more in the promotion and protection of the business interests of their drafters.

As clients and local authorities began to increasingly demand carbon neutral buildings, the need for a genuine “paradigm shift” in design became clear.

Up to the turn of the 21st century efficiency was believed to lie at the heart of low-carbon building design but efficiency in building energy system design is largely about machines. The secret of real low carbon buildings lies largely in their design and construction. The end of the age of buildings that were “machines for living in” was nigh.

Architects began to understand that low carbon buildings needed to: halve the demand for energy with good architecture; double the efficiency of the machines in the building; halve the carbon intensity of the energy used to run the machine; and get the rest of the greenhouse gas savings through load shaving and shifting and behavioural changes by occupants.

In this way buildings could be run on a fraction of energy with over 90 per cent fewer resulting emissions.

But to achieve this, integrated renewable energy systems had to be developed. Some farsighted individuals had been experimenting with wind and solar energy and heat pump systems since the oil shocks of the 1970s.

The great thing about the early low carbon buildings like the Oxford Ecohouse was that they demonstrated that once the initial capital investment has been made, integrated renewable systems produced energy that never increased in price.

By 2015 we had the $300 barrel of oil and the vulnerable poor in Britain were already dying in large numbers in winter from hypothermia and in summer from heat stress.

The problem was made worse by the huge investments in a new generation of nuclear and coal-fired power stations that forced up the cost of delivered energy to astronomical levels, and caused widespread chaos when the electricity grid failed during extreme weather events.

Some reports early in the century demonstrated how we could have reduced emissions from UK homes by 60-70 per cent with an investment of around 200-250 billion. That was around 10 billion a year each year for 10 years.

This was a fraction of the losses of the banking system at that time and would have covered the installation of widespread energy efficiency measures and solar systems in most UK homes.

But by the 2020s, we had learned how the power of solar energy could be harnessed to supply so many of our energy needs. Back then in the UK, each square metre of a south-facing roof received around 1000 kWh of solar radiation during a year, and today, of course, this is around 1200kWh.

This means that the roofs of most homes receive more energy from the sun in a year than is needed to provide their space and water heating and electrical energy.

Even in rainy Scotland a myth was proved very wrong – that there was not enough sun in northerly latitudes to make solar energy worth the investment. The radiation that falls on UK roofs is now used to supply over 60 per cent of all building needs in lighting, heating and air conditioning.

What eventually proved to be the trigger for change in this field was the involvement of cities. They did not suffer from the myopia and a four/five year elected executive and were directly accountable to their local voters. Everyone could see where the buck stopped.

Oxford was an early solar city, convinced by the success of the Oxford Ecohouse project. The Oxford Solar Initiative brought together business, government, planning, and citizens to make solar power happen in the city.

In 2003, the city had several clear objectives, including that 10 per cent of all houses in Oxford should have solar systems by 2010 and the implementation of a solar campaign to support local reduction initiatives at every level within the Oxford community from primary school children to business leaders.

From such simple aims grew the Oxford Solar Initiative and similar city initiatives around the world. Gradually the allegiances and technologies were built that provided the firm foundations for the low carbon economy we enjoy today. We now have the technology to survive in comfort in buildings and cities that are resilient to the twin challenges of climate change and fossil fuel depletion without the need to develop unaffordable and unclean generating capacity.

&#149 Susan Roaf is Professor of Architectural Engineering at Heriot- Watt University. Her paper is one of a series commissioned by the David Hume Institute, Edinburgh University, which will be discussed at a seminar at Our Dynamic Earth, Edinburgh, tomorrow. Information can be found at www.davidhumeinstitute.com