Eco Building Standards
As part of the UK Governments commitments to reduce overall CO2 emissions and their binding commitments under the Kyoto Protocol they have set more rigorous targets for reducing emissions from homes.
The ‘Code for Sustainable Homes’ (CSH) was released in December 2006.
The CSH is an environmental impact rating system for housing in England & Wales, setting new standards for energy efficiency and sustainability which are not mandatory under current building regulations.
It includes a minimum level of energy and water efficiency as well as standards for waste, reducing impacts on health and ecology amongst others.
The code has six levels. Level 1 means an energy performance 10% better than the Building Regulations; Level 3 requires a 25% improvement and Level 6 is a Zero-carbon Home (ie. Zero-carbon emissions from ALL energy use in the home, including appliances and electrical equipment)
The Government has set a target for all new homes to be zero-carbon by 2016.
The Energy Efficiency Best Practice in Housing Programme (EEBPH) sponsored by the Government publishes, Good, Best and Advances practice to encourage developers to exceed those energy efficiency minimum standards laid out by Building Regulations.
Advanced Practice represents a 60% reduction in emissions and is related to the Passivhaus standard which has become established in Germany and Northern Europe.
The term ‘Passivhaus’ refers to a specific construction standard for buildings which have excellent comfort conditions in both winter and summer. Passivhaus dwellings typically achieve an energy saving of 90% compared to existing housing.
The website www.passivhaus.org.uk defines the standard:
A dwelling which achieves the Passivhaus standard typically includes:
· very good levels of insulation with minimal thermal bridges,
· well thought out utilisation of solar and internal gains,
· excellent level of airtightness,
· good indoor air quality, provided by a whole house mechanical ventilation system with highly efficient heat recovery
By specifying these features the design heat load is limited to the load that can be transported by the minimum required ventilation air. Thus, a Passivhaus does not need a traditional heating system or active cooling to be comfortable to live in – the small heating demand can be typically met using a compact services unit which integrates heating, hot water and ventilation in one unit (although there are a variety of alternative solutions).
For Europe (40o – 60o Northern latitudes), a dwelling is deemed to satisfy the Passivhaus criteria if:
· the total energy demand for space heating and cooling is less than 15 kWh/m2/yr treated floor area;
· the total primary energy use for all appliances, domestic hot water and space heating and cooling is less than 120 kWh/m2/yr
At the time of writing there is about half a dozen Passivhaus certified homes in the UK with about 20 more in the pipeline.
The reasons for why the UK has been so slow to adopt the standards are unknown. It may be to do with the lack of a publicly funded body to promote best practise in construction or the fact that the Government’s Code for Sustainable Homes has gone in a different direction (with a focus on renewables). The Passivhaus house approach in some instances can be a more cost effective approach rather than expensive microrenewables.
However the standard is fast becoming a more acceptable and discussed standard for those self builders looking to build a sustainable home in the UK, and is a proven standard which I am sure we are gong to hear a lot more about in the future.