Improved building requirements for new build from 2001 - 2015

In 2001, there were 2,186,000 dwellings in the South West of England (ONS, 2003b). Total domestic energy consumption was approximately 46,931 GWh. This corresponds to over 12.6 million tonnes of CO₂ emissions (see Table 1).

Dividing total domestic energy consumption in the South West in 2001 by the number of individual dwellings in the region, gives an average energy consumption of approximately 21,500 kWh per dwelling. Obviously, this average figure masks a huge variation in actual energy consumption in individual properties (and corresponding CO₂ emissions) – this is dependent on a variety of factors including:

• Type of dwelling (detached house, terraced house, apartment etc.).
• Number of occupants.
• Age and construction of dwelling.

An estimate of how this energy was used for different purposes in the home is shown in Table 1.

Table 1
Estimated energy consumption by purpose, per dwelling, in 2001

Purpose	Total South West (GWh)	Per dwelling (kWh)	Per dwelling (tonnes CO2 )
Total domestic energy consumption	46,931	21,500	5.8
of which…
Space heating	26,785	12,250	3.3
Water heating	10,059	4,600	1.2
Cooking, lighting & appliances	10,083	4,650	1.3
Sources: AEAT, 2001 & 2003; DETR, 1996; DTI, 2002, 2003 & 2004; Mitchell & Regen, 1998; ODPM, 2001; ONS, 2003b; REWARD, 2004; Transco, 2003 and Western Power, 2004

General housing and domestic energy assumptions

• All dwellings that existed in 2001 will still exist in 2015, i.e. new dwellings are additional and do not replace existing dwellings that have been removed from the housing stock.
• Domestic electricity consumption will increase 1% per year between 2001 and 2015, based on an expected 9% growth between 1998-2010 (Fawcett et al., 2000). Growth is due to increased numbers of appliances and expansion in the area of electronic home entertainment, such as digital television (see 'Additional Information' on www.sdfhsfhsiuhfsdoi for discussion on the CO₂ emissions).
• The CO₂ emission factor changes from 0.43 kg CO₂ / kWh in 2001 to 0.36 kg CO₂ / kWh in 2015, due to a change in the technologies used to generate electricity.

Using the above assumptions, base case domestic energy consumption figures and associated CO₂ emissions were derived. The base case figures for domestic energy consumption by the South West's housing stock, in 2001, are presented in Table 2.

Table 2
Domestic energy consumption and CO₂ emissions in the South West, by fuel type, in 2001

Fuel type	Base case: 2001
	Total housing stock (GWh)	CO2 (tonnes)
Total	46,931	12,633,297
of which…
Electricity	13,967	6,005,776
Gas	27,969	5,314,110
Solid fuel	1,909	572,600
Petroleum	3,087	740,810
Sources: ONS, 2003b and SWRA, 2003

The base case ecological footprint of domestic energy use in 2001 was 0.71 gha per person.

Scenario 1: Current building regulations

What is the effect on domestic energy consumption and CO₂ emissions if all new homes in the South West are built to current minimum requirements: Building Regulations 2002?

The following variables were assumed:

• A regional population growth rate of 12.5% between 1981 and 2000. To cope with this increase in population, the region has a target of 20,200 dwellings to be built each year. If this target is achieved, total dwellings in the South West will increase from 2,186,000 in 2001 to 2,468,900 in 2015 assuming all new dwellings are additional (SWRA, 2003).
• Typical houses built to Part L Building Regulations, with a floor area of 80m 2 , would produce approximately 1.8 tonnes of CO₂ emissions from space heating (ODPM, 2004a) .
• An additional 2.3 tonnes of CO₂ are likely to be emitted annually, due to increased energy use for hot water, lighting, cooking and appliances (ESD, 2004a).

This means that existing housing stock, plus new homes built to current minimum requirements, would generate 13.5 million tonnes of CO₂ emissions by 2015. Table 3 summarises the findings for Scenario 1.

Table 3
Estimated CO₂ emissions generated by existing stock and new homes in the South West, based on current building regulations, in 2015

Fuel type	Base case: 2001	Scenario 1
Total	12,633,297	13,541,474
of which…
Electricity	6,005,776	6,122,114
Gas	5,314,110	6,105,950
Solid fuel	572,600	572,600
Petroleum	740,810	740,810
Sources: ONS, 2003b and SWRA, 2003

This scenario gives a domestic energy ecological footprint in 2015 of 0.76 gha per person, an increase of 0.05 gha per person (7%) from the 2001 base case.

Scenario 2: Higher energy efficiency standards

What is the effect on domestic energy consumption and CO₂ emissions if all new homes are built to higher energy efficiency standards?

The following variables were assumed:

• 20,200 dwellings to be built each year (SWRA, 2003) – as per Scenario 1.
• Based on an energy efficient housing association scheme in London. Houses were built on a layout to maximise passive solar gains, used traditional masonry for construction with wide, fully insulated cavities and gas fired central heating systems incorporating condensing boilers (EST, 1999).

This means that the existing housing stock, plus new homes built to higher energy efficiency standards than current minimum requirements, would generate 13.1 million tonnes of CO₂ emissions by 2015. Table 4 summarises the findings for Scenario 2.

Table 4
Estimated CO₂ emissions generated by existing stock and new homes in the South West, based on high energy efficiency standards, in 2015

Fuel type	Base case: 2001	Scenario 2
Total	12,633,297	13,088,994
of which…
Electricity	6,005,776	6,122,114
Gas	5,314,110	5,653,470
Solid fuel	572,600	572,600
Petroleum	740,810	740,810
Sources: ONS, 2003b and SWRA, 2003

This scenario gives a domestic energy ecological footprint in 2015 of 0.74 gha per person, an increase of 0.03 gha per person (4%) from the 2001 base case.

Scenario 3: Zero Emission Development (ZED) standards

What is the effect on domestic energy consumption and CO₂ emissions if all new homes in the South West are built to ZED standards?

The following variables were assumed:

• 20,200 dwellings to be built each year (SWRA, 2003) – as per Scenario 1.
• Houses have a net zero fossil fuel energy demand, and are designed to reduce energy demand for space heating and cooling. Residual energy demand (for hot water, lighting, cooking and appliances) is met from on-site renewable energy generation (for example, from wind turbines, biomass CHP and/or photovoltaics).

his means that existing housing stock would continue to generate 12.6 million tonnes of CO₂ emissions in 2015. The additional new homes built to ZED standards would not add to the CO₂ emissions. Table 5 summarises the findings for Scenario 3.

Table 5
Estimated CO₂ emissions generated by existing stock and new homes in the South West, based on ZED standards, in 2015

Fuel type	Base case: 2001	Scenario 3
Total	12,633,297	12,633,297
of which…
Electricity	6,005,776	6,005,776
Gas	5,314,110	5,314,110
Solid fuel	572,600	572,600
Petroleum	740,810	740,810
Sources: ONS, 2003b and SWRA, 2003

This scenario gives a domestic energy ecological footprint in 2015 of 0.71 gha per person, the same as the 2001 base case.