Houses are being built, even during these hard, economic times, in particular in the self-build market. These homes tend to be more bespoke, and often the client wants them to achieve higher standards of energy efficiency. So I have put together a brief summary of how rainwater harvesting can help.

The Code for Sustainable Homes was introduced by the Government to drive a step‐change in sustainable home building practice. It is a standard for key elements of design and construction which affect the sustainability of a new home. It has become the single national standard for sustainable homes, used by designers and builders as a guide to development, and by home‐buyers to assist their choice of home. The Code provides 6‐levels of sustainable performance, and is aimed principally at reducing carbon footprint.

However, pressures on national water supplies are also recognised by the inclusion of mandatory reductions in the use of mains water to be achieved before a particular Code rating can be awarded.

Achieving the Code:
The guidance below provides advice on achieving the mandatory requirements of the Code for Sustainable Homes, in relation to mains water consumption.

Code Levels 1 and 2:
Although it varies widely from region to region, the generally accepted average per‐capita mains water consumption throughout the UK is around 150 litres per day. As the per capita rainfall in the south of England, for example, is less than can be found in some parts of the Mediterranean, this level of consumption is not sustainable, particularly as the population grows. However, it can be achieved without rainwater harvesting.

Code Levels 3 and 4:
This is the standard that new‐build public housing, such as the developments being commissioned by Housing Associations, must achieve by 2010. All private‐sector developments will have to achieve level 3 which means it is mandatory that mains‐water consumption be reduced to 105 litres per person per day.

This could be achieved simply by installing smaller baths. However, for many potential home‐buyers this might be a significant disincentive to purchase. Fitting a rainwater harvesting system, even on smaller properties, would provide a cost‐effective alternative to unpopular small baths.

Code Levels 5 and 6:
This standard will become mandatory for Housing Associations by 2013, and for the private sector by 2016. At this level of the required mains water consumption is reduced to 80 litres per person per day. The only realistic way of achieving such a reduction in mains water consumption is by using re‐claimed water, such as that provided by rainwater harvesting, with a bespoke approach being taken to each development.

This blog's facts:
1). In a 100 year period, a water molecule spends 98 years in the ocean, 20 months as ice, about two weeks in lakes and rivers, and less than a week in the atmosphere.
2). Germany harvests 100 times more rainwater than the UK.
3). Only 1 per cent of the earth's water is available for drinking.

About the author: Barry Nutley is co-founder and director of Viridis Energie Consultants

If you have a question about anything in the above blog, please ask it in the comments section below.