Climate change brought about by man-made emissions of greenhouse gases has been identified as the greatest challenge facing human society at the beginning of the twenty-first century. Each person in the UK is responsible for around ten tonnes of greenhouse gas emissions per year. Stabilising global greenhouse gas {GHG} emissions at a sustainable level would involve reducing UK GHG emissions to two tonnes
per person per year.

Climate Change: The Greenhouse Effect
The complex mechanisms of climate change involve the balance of carbon in the atmosphere, in the oceans and in all living things. The main mechanism is the greenhouse effect, by which levels of greenhouse gases in the atmosphere affect the heat balance of the earth. The major greenhouse gases are carbon dioxide, nitrous oxide and methane. There is an overwhelming scientific consensus that climate change is taking place as a consequence of man-made
greenhouse gas emissions. A recent report by the United Nations Intergovernmental Panel
on Climate Change confirms that global greenhouse gas emissions increased by 70% and carbon dioxide emissions by 80% between 1970 and 20041.

The Effects of Climate Change
The effects of climate change are complex. They include:
Increased average temperatures
Rising sea levels {because of the melting of glaciers and of polar ice caps}
Increased precipitation
More frequent extreme weather events.

UK Carbon Dioxide Emissions

Although the graphs suggest that emissions are being reduced, measures to cut emissions are being inhibited {and in some cases cancelled out} by growth in economic activity, and associated growth in the number of dwellings, the amount
of industrial and commercial floorspace, the number of vehicles etc. Tackling Climate Change
Action to address climate change falls into two categories: mitigation policies are designed to reduce greenhouse gas & emissions to slow down or stop climate change; adaptation
policies are designed to adjust society to cope with climate changes that are already happening or are likely consequences of current GHG emissions.
The UK’s national target under the Kyoto Protocol is to reduce greenhouse gas emissions by 12.5% by 2012 {based on 1990 levels}.
The UK Government has also adopted a voluntary target to reduce emissions by 20% by 2010 {based on 1990 levels}.

The Contribution of Buildings to Greenhouse Gas Emissions
Housing
There are approximately 25 million domestic buildings in the UK. The stock has grown from 18 million in 1976 and is expected to reach 27 million by 2020 – 50% growth in less than 50 years.
Despite measures to improve the energy efficiency of dwellings, carbon dioxide emissions are rising, mostly because of a significant increase in the numbers of electrical and electronic appliances in homes, increasing household numbers and a
tendency to heat our properties to higher temperatures. The replacement rate of the existing domestic stock is less than 1% per year. Emissions from the existing stock dominate – accounting for 99.7% of the total. At the current rate of turnover of the stock, 80% of the dwellings that exist today will still exist in 20502. This means it is impossible
for the UK to meet its carbon emissions reduction targets without an extensive programme of improvements to the energy efficiency of existing dwellings.

Non-Domestic Buildings

The number of non-domestic buildings in the UK is difficult to estimate. However, best estimates suggest that in 1994 there were approximately two million non-domestic premises in the UK. Some premises embraced several buildings {e.g. college
campuses} and some formed only part of a building {e.g. office suites in a multi-tenanted of
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