So many small prefabs and sheds on TreeHugger and other sites, but how many are zero energy and carbon neutral? Energyspace builds "a state of the art workspace that makes a minimal or zero contribution to global climate change in every aspect of its design, construction, energy-use, and life cycle."
They are super-insulated (hemp-cotton batts are an option), sited for passive solar gain but assisted by wood fired stoves and photovoltaics.
They give very good reasons for building a garden shed, most of which are as applicable in North America as they are in the UK:
Garden buildings: the benefits?
The arguments for a garden office are convincing:
* The addition of valuable new living or working space which frees up room in your home
* Return on investment. It is estimated that one can recuperate 75% - 100% of the cost of the project on the value of your house.
* A garden building is considered as 'plant' and usually tax deductible.
* Avoiding the rush hour traffic. Saving money and time as well as CO² emissions by not having to travel to work.
* Interruptions are less likely in a garden office than in an office in the home itself - the distinction between home life and work is essential for those working from home.
* Subject to specific limits and exceptions planning permission is not normally required for garden buildings provided the building is for a purpose 'incidental' to the dwelling house use.
A garden office creates extra space without the disruption to home life that an extension or loft conversion entails.
What is 'zero carbon' or 'carbon neutral' construction?
Firstly, one has to achieve 'zero heating'. This means that the building is insulated and draught proofed to a set of standards that are such that the heating requirements of the occupants are met by solar gains through windows, as well as the heat emitted by appliances and people.
Once 'zero heating' has been achieved, one has to tackle the emissions associated with electricity use for appliances. 'Zero carbon' means that the building must create zero net emissions of carbon dioxide over its lifetime. So, energy used must be 'paid back' through the use of renewable energy systems that are designed into the building.
Which suppliers of garden buildings aim for zero carbon?
At present Energy Space is the only provider.
Some of the better quality garden offices on the market aim for the thermal performance required by the 2002 UK Building Regulations. Our buildings aim to exceed this standard as explained below.
Energy Space aims at the exemplary thermal standards seen in Germany and Sweden.
Building energy performance can be explained using the following measurement:
* Kilowatt hours - per metre squared - per annum (KWh/m²/a)
The average UK home (80 square metres semi-detached) uses 278 kilowatt hours per mtr2 per annum (278kwh/m²/a) for heating, lighting and appliances. Built to 2002 Building Regulations the same size of home uses around 200kwh/m²/a (the standard most other garden offices aim for). Our LES range aims at 84kwh/m²/a while our ZES aims at 38kwh/m²/a.