The Code for Sustainable Homes (CSH) is a set of guidelines introduced by the Communities and Local Government department to establish a national standard for the sustainable design and construction of new homes. From May 2008 it has been mandatory for all new homes to be rated against the code and this information is then included in the Home Information Pack (HIP). The CSH gives new hom ebuyers better information about the environmental impact of their new home and it’s potential running costs, and offers builders a tool with which to differentiate themselves in sustainability terms. The ultimate aim of the CSH is to make all new homes carbon neutral by 2016. The code measures new housing across 9 categories to establish the sustainability of a home and its environmental impact.
There are a total of 29 credits available for Energy and CO2 emissions. This represents 36.4% of the total available performance, making it the largest single category. 15 of the 29 credits available are awarded for the category ENE 1 Dwelling Emission Rate. In addition to the credits available, specific mandatory levels must be achieved to allow certification of a building overall at a specific level.
Credits are awarded based on the percentage improvement in the Dwelling Emission Rate (DER), (estimated carbon dioxide emissions in kg per m2 per annum arising from energy use for heating, hot water and lighting for the actual dwelling), over the Target Emission Rate (TER) (the maximum emission rate permitted by Building Regulations), for the dwelling where DER and TER are as defined in AD L1A 20065 Edition of the Building Regulations.
CSH Section ENE 7 provides provision for Low or Zero Carbon (LZC) technologies. The aim of this category is to reduce carbon emissions and atmospheric pollution by encouraging local energy generation from renewable sources to supply a significant proportion of the energy demand. This category is worth 2 credits and is achieved through producing at least 10% of the buildings energy needs using LZC technologies.
Solar Photovoltaics (PV) are an ideal way to achieve this as it can be integrated into the fabric of the building, has little visual impact and requires little ongoing maintenance.
Worked Example of how to achieve CSH Level 4:
An average 3 bed, family home may be expected to use 6,000kWh/yr for lighting, heating and hot water. Based upon all of this being taken from the grid (with an emissions factor of 0.422 kgCO2/yr), the building will have a TER of 2,532 kgCO2/yr. To achieve Level 4 under the CSH, the developer will need to reduce this by at least 44% (1,114 kgCO2/yr). This can be done using solar PV. The solar PV system will need to generate 1,962 kWh/yr (based upon an emissions facto
r of 0.568 kgCO2/yr). To do this the developer will need to install a 2.4kWp solar array, producing 2,000kWh/yr (calculated using Standard Assessment Procedure for a south orientation at an angle from the horizontal of 30°).
EvoEnergy have experience of working on projects trying to achieve levels 4-6. An example would be the
Stoneguard house (pictured right) built for the
Creative Energy Home Project.
BREEAM
Renewable energy technologies also form an important part of BREEAM (BRE Environmental Assessment Method). BREEAM is the leading and most widely used environmental assessment method for buildings. It sets the standard for best practice in sustainable design and has become the de facto measure used to describe a building's environmental performance. BREEAM has different standards to measure different types of buildings by e.g. BREEAM Office, BREEAM Education.
Criterion ENE 5 of BREEAM Office provides for provision of LZC technologies. UP to 3 credits are available for the implementation of these technologies. For the full 3 credits, the technology must result in a 15% reduction in the CO2 output of the building. The generation of energy onsite will also contribute towards the maximum 15 credits available for low energy usage. Solar PV is a great way to meet this benchmark as it has minimal visual impact, works excellently in an urban environment and is easy to incorporate as part of the building’s design.
LEED
Leadership in Energy and Environmental Design (LEED) is an alternative set of standards for building properties. Developed by the U.S. Green Building Council (USGBC), this standard provides an internationally recognised level of building development, certified against peer agreed standards. There are 35 credits available for Energy and Atmosphere. On-site Renewable Energy form contributes 4 credits and can be an important step in helping to reach LEED certification.
BREEM vs LEED summary .pdf