There are many claims for green buildings but how do you know which ones really mean something? As a scientist I look for evidence particularly in relation to a recognised standard. We claim that our garden offices, studios and workshops are low energy because we design them to at least achieve the standard of insulation required for new housing as defined in Part L of the Buuilding Regulations. Most clients opt for the Penthouse 100 spec but some are persuaded by the higher level of comfort and reduced heating costs from adopting the higher Penthouse 150 spec.

specifications

¹ Building Regulations Part L 2002

² U value calculation: BRE U value calculation version 1.08. Calculation method: BS EN ISO 6946

For larger buildings there are several standards which are worth considering.

http://www.breeam.org/

The Government issued the Code for Sustainable Homes last year which, as the name suggests, relates to housing with Level 3 the minimum required for publicly funded housing and Level 6 the aspirational goal.

http://www.communities.gov.uk/planningandbuilding/buildingregulations/legislation/englandwales/codesustainable/

Finally and, in my view, most relevantly, there is the system being promoted by the Association of Environmentally Conscious Builders (AECB).  This is very simple to understand with both a prescriptive and performance based approach and plenty of practical advice on how to use the standards.  Essentially Silver should be the minimum to which anyone considers building with the Gold standard somewhat higher in performance than even the German Passiv Haus standard.

http://www.carbonlite.org.uk/carbonlite/

Whether you adopt one of these standards as a goal in its own right or use the guidance as a way of improving an existing design, the benefits can be significant.  As with all building, incorporating energy saving measures at an early stage in the design is far easier than adaptation or retrofit in the future.  And, in most cases, the premium can be as low as 5-15% of the capital cost for a lifetime of savings.

Although all of our garden buildings have been bespoke to date, there are economies to be had in sticking with a standard design.  Also, because the planning rules changed 1 October 2008, there is a need for low rise structures which can be placed within 2 metres of boundaries so, our standard units are designed to meet this requirement.

If you need to check on planning issues, there is a great site: www.planningportal.co.uk

The Vivid Green philosophy of high levels of insulation plus good quality windows and doors still apply in our standard unit but, with standardising sizes, colours etc allows us to pass on discounts to customers.

There are two units in the range, the Penthouse 8 with 8 sq metres of floor space and a very contemporary, five sided look and the Penthouse 7.5, a rectangular building with 7.5 sq metres of floor space.  Both units have a porch and the Penthouse 8 has two bays for a window seat (with the potential for storage under) and desk whereas the Penthouse 7.4 has just one bay.

Both units are installed with surface mounted electrics, internal lighting, clad in treated Larch or Douglas Fir with a rubber membrane for the roof covering with a 15-20 year life.

The Penthouse 8 is priced at £9,890 and the Penthouse 7.5 at £9,530 (inclusive of VAT, delivery and installation in Herts, Beds and Bucks plus London, North of the Thames).

Penthouse 8

A striking, contemporary design with 'letter box' windows, a large porch and two bays

Penthouse 7.5

A high quality space with one bay and large single door