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Eco-towns Development Houses

Homes are responsible for more than a quarter of the UK's carbon emissions and consume about a third of all the energy produced in the UK. The Government wants to build three million new homes by 2020 at a rate of about 240,000 per year. By 2016 all new homes must be zero carbon.

In March 2007 the Government announced that it would consider Local Authority proposals for eco-towns. These should be zero-carbon developments built on brownfield sites. They would include between 5,000 and 20,000 homes and have good transport links to nearby towns and cities.

In October 2007 the Government announced that it would support the development of ten eco-towns in England with a total of 200,000 new homes.

The Government's key criteria include:

the developments should use of brownfield sites

the houses must be zero carbon

at least 30% of the homes must be ‘affordable'

the developments must be mixed use including dwellings, shops, businesses, schools etc

the development should have minimum impact on the local ecology

there must be good public transport links to nearby towns and cities

new technologies must be used such as district heating, combined heat and power, wind energy, solar photovoltaics, ground source heat pumps, solar water heating etc.

See: www.communities.gov.uk/documents/housing/pdf/ecotowns

In April 2008 the Government announced a short list of 15 locations from those that had been submitted. The ten sites for development will be selected from this list by the end of the year. The Government wants half of these developments to be completed by 2016 and the remainder by 2020.

The Government's proposals have proved to be controversial. Although it is widely accepted that new housing needs to be built to higher energy standards than most existing buildings, there are many problems including:

concerns that eco-towns will not go through the proper planning process

some of the proposed developments are on greenfield sites

not enough affordable homes will be included

the homes will not be zero carbon

the developments will cause congestion on already overloaded roads

some of the sites are too isolated so residents will use cars rather than public transport

Zero carbon homes

In December 2006 the Government published Building a Greener Future: Towards Zero Carbon Development. The measures outlined included:

improving the energy efficiency requirements of new homes

publication of a Code for Sustainable Homes

See: http://www.communities.gov.uk/documents/planningandbuilding/pdf/153125

A zero carbon house is defined as a having:

"zero net emissions of carbon dioxide from all energy use in the home".

This includes energy consumed by appliances such as TVs and cookers, as well as those that are currently part of building regulations, such as space heating, hot water and ventilation.

The construction of new zero carbon homes will play an important part in achieving the government's target to cut CO₂ emissions by at least 60% by 2050. However, by that date it is expected that about 75% of the current housing stock in the UK will still be in use.

For this reason the main challenge facing the government is the upgrading of the environmental qualities of existing houses. This includes the installation of much more insulation and more efficient heating systems.

The Code for Sustainable homes

From April 2007 the Code for Sustainable Homes applied for new build, publicly funded, multiple dwellings. It introduces minimum standards for the efficiency of energy and water use. The Code measures the sustainability of dwellings against key design features and rates the building on a scale of 1 to 6. The minimum standards for compliance with this code are higher than those in the Building Regulations. The key design features include:

Energy

Water

Materials

Waste

Pollution

From May 1 2008 compliance is required for all new homes.

See: http://www.planningportal.gov.uk/england/professionals/en/1115314116927.html

Zero carbon homes

A zero carbon house was defined as a having zero net emissions of carbon dioxide from all energy use in the home. This effectively means that a zero carbon home must generate as much energy as it uses.

To achieve this, the design must reduce the energy requirement and include renewable energy generation.

reduce the energy requirement

This can be achieved in the following ways:

design the building to be airtight

include draft lobbies at entrances to reduce the loss of heat

include high levels of insulation in the ground floor, roof and external walls

use ventilation and heat recovery systems to distribute the heat generated within the house in bathrooms and kitchen

orient the building for maximum solar gain - see next section

use well insulated external doors

use double or triple glazed windows

use energy efficient appliances such as washing machines and fridge/freezers

use low energy lighting

insulate all hot water pipes and storage cylinders

include renewable energy generation

solar water heating

ground source heat pumps

biomass

photovoltaic cells

wind turbines

In addition, the energy used in the production of the construction materials and the construction process should also be considered. This is known as the embodied energy. For example:

Natural insulation made from sheep's wool or recycled newspaper has a much lower embodied energy than polystyrene or polyurethane.

Locally sourced materials should be used to reduce the energy used in transporting them to the construction site.

Zero carbon homes - site layout

The British Research Establishment (BRE) Report 209, 1991 - Site Layout Planning for Sunlight and Daylight, studied the layout of housing estates related to sunlight. This was followed up in 1992 with an Information Paper - IP4/92 Site Layout for Sunlight and Solar Gain.

These studies showed that careful consideration of the positioning and orientation of houses and landscaping features can help the houses take best advantage of the available sunlight thus reducing their energy needs. To achieve this:

Houses should be oriented so that the elevation with the largest glazed area should face within 30 ^o of south.

Shading of houses by other houses or vegetation should be avoided.

Roads should preferably run east to west.

The BRE Housing Design Handbook, 1993 describes considerations relating energy use to the internal layout of houses. In 1994 the Architectural Association published Solar Energy in Housing Design Volumes 1 and 2.

These studies have shown that careful consideration of layout of rooms in a house can also help to reduce their energy needs. To achieve this:

The most frequently used rooms requiring heating, such as living rooms, dining rooms and main bedroom should be southerly facing.

Rooms that require little sunlight such as hall, utility room and bathrooms should be northerly facing.

Kitchens require smaller amounts of glazing if located on the south side of the building as they gain heat from the cooking activities.

Lobbies, utility rooms and garages can be used as buffer zones between the outside and the internal heated areas to prevent heat loss.

Although these requirements are relatively restrictive in the orientation of the building and location of rooms within it, they still leave the designer with many choices in both the housing estate layout and floor plan arrangements.

See: www.sei.ie/getFile.asp?FC_ID=974&docID=698 for more details.

Zero carbon homes - water heating, space heating and power generation

In the UK, the house construction sector can make a significant contribution to reducing the UK's CO₂ emissions. This can be achieved by making all new buildings more energy efficient and including renewable energy technology.

These considerations include:

solar water heating see: www.heatingguide.co.uk/solar-heating.php

This can provide up to two thirds of a dwelling's water needs. A thermal collector, located on the roof, absorbs energy from sunlight and heats the liquid flowing within it. The roof should be unshaded and southeast to southwest facing. The heated liquid passes through a coiled pipe within the hot water cylinder where the heat is transferred into the domestic hot water supply. In winter, although the panel can help to warm the water, another back up heater will be required. For a three bedroomed house 3 to 4 square metres of panels are required.

heat pump water heating see: http://www.nef.org.uk/gshp/documents/CE82-DomesticGroundSourceHeatPumps.pdf

Ground source heat pumps use a buried pipe which transfers heat from the ground into a liquid flowing within it. The heat, which is extracted through a heat exchanger, is used to provide space heating. The pumps are most efficient when operating a heating system running at a relatively low temperature. For this reason they are best suited to under floor heating. The pump requires electricity to drive it. This can be provided by renewable sources such as wind or solar.

biomass water heating see: http://www.wrexham.gov.uk/assets/pdfs/planning/renewable_energy/no7.pdf

These systems extract energy by burning wood fuels. The three main types of fuel are logs, wood chips and wood pellets (manufactured from wood waste). Generally these are better suited to central systems servicing several dwellings rather than being installed in individual houses.

solar electricity generation see: www.heatingguide.co.uk/solar-electricity.php

These systems use the energy from sunlight to directly generate electricity by means of a photovoltaic cell. Direct current is generated which is changed into alternating current for use in the dwelling by an inverter. As well as panels containing photovoltaic cells they can also be manufactured as tiles or slates that can be fitted to a roof less conspicuously. About 10 square metres of panels are needed per kilowatt of electricity generated. As for solar heating panels the roof should be unshaded and southeast to southwest facing.

wind electricity generation see: www.heatingguide.co.uk/wind-turbines.php

Wind turbines take the energy from the wind and convert it into electricity. As with solar power systems, direct current is generated. This is changed into alternating current for use in the dwelling by an inverter. A typical domestic system would be between 1 and 6 kilowatts.

Assessment

Eco-towns

Questions 1 to 5 - Select the correct response for the following questions

1. Which of the following is not one of the Government's key criteria for eco-towns?

Athe developments should use brownfield sites

Bthe houses should be zero carbon

Cthe development should have minimum impact on the local ecology

Dat least 70% of the homes must be affordable

2. Which of the following is not a common concern relating to eco-towns?

Aeco-towns may not go through the proper planning process

Bsome of the proposed developments are on greenfield sites

Cnot enough affordable homes will be included

Dthe homes will be zero carbon

3. Which of the following is not a key design feature included in the Code for Sustainable Homes?

AEnergy

BCost

CWater

DMaterials

4.Which of the following is not a normal method of reducing the energy requirement of a new home?

Ause a ventilation and heat recovery system

Binclude high levels of insulation in floors, roof and external walls

Climiting the home to four rooms

Duse double or triple glazed windows

5.Which of the following is not a way of reducing energy needs in relation to the orientation of a home?

Autility rooms and bathrooms should be southerly facing

Bthe most frequently used rooms should be southerly facing

Ckitchens require smaller amounts of glazing if they are southerly facing

Dutility rooms can be used as buffer zones to reduce heat loss

Questions 6 to 10 - Decide whether each statement is True (T) or False (F).

6.i) Homes are responsible for more than a quarter of the UK's carbon emissions and consume about a third of all the energy produced in the UK.

ii) The Government wants to build three million new homes by 2020 at a rate of about 240,000 per year.

Which option best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Cii)Fii)T

Dii)Fii)F

7.i) Construction of zero carbon homes will play an important part in achieving the government's target to cut CO₂ emissions by at least 60% by 2050.

ii) By 2050 it is expected that about 25% of the current housing stock in the UK will still be in use.

Which of the following options best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Cii)Fii)T

Dii)Fii)F

8.i) Houses should be oriented so that the elevation with the largest glazed area should face within 30 ^o of north.

ii) Shading of houses by other houses or vegetation should be avoided.

Which of the following options best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Ci)Fii)T

Di)Fii)F

9.i) In the UK, the house construction sector cannot make a significant contribution to reducing the UK's CO₂ emissions

ii) Ground source heat pumps are most efficient when operating a heating system running at a relatively low temperature.

Which option best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Ci)Fii)T

Di)Fii)F

10.i) Solar water heating can provide up to two thirds of a dwelling's water needs

ii) Biomass heating systems are better suited to individual houses rather than central systems servicing several dwellings.

Which of the following options best describes the two statements?

Ai)Tii)T

Bi)Tii)F

Ci)Fii)T

Di)Fii)F

Assessment

Eco-towns

Solutions

Checklists

The Government has produced home heating and commercial building checklists to enable building owners to assess the energy efficiency of their heating and hot water systems. The checklist should be completed by a heating engineer during a service or maintenance visit.

It gives the building owner a simple assessment of the efficiency of their heating and hot water systems and an assessment of what savings could be made.

For a checklist for gas fired heating systems see:

http://www.communities.gov.uk/documents/planningandbuilding/pdf/gasfiredchecklist

For an overview of building control technology see:

http://www.carbontrust.co.uk/publications/publicationdetail?productid=CTV032

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