The Greenwood Centre’s Woodland College

The GWC is a nationally renowned educational charity, working to promote coppice and green wood crafts, and management of deciduous woodlands. It runs a variety of social forestry courses. We have been involved with various building projects at the GWC since 1995, when we were commissioned to design the Woodland College. This building prioritised use of local timber alongside modern energy efficient timber frame construction. In 2006 the building was extended to form a cafe / shop area and as part of a whole site solution is heated via a hot water main supplied by a small biomass unit. We worked with David Olivier (EAA) as energy consultant on this project.

“we consider the building to be the heart of the Green Wood Centre, and that it epitomises all that we represent, in terms of sustainability, low energy use, its many and varied uses of timber and green wood, and the relaxation people feel when they use the building.” Judy Walker, Director of the Green Wood Centre.

This timber framed building is (still!) one of the most energy efficient in the country. It is a modest classroom and office building, with associated toilets and shower, and store rooms. The classroom contains an innovative pole framed structure which our practice worked on site to build. The college building was completed in 1999.

Other features include:

• locally sourced and processed timber
• cellulose insulation
• on site treatment of sewage using settlement tank, reedbeds and pond
• low flush wc’s
• low VOC paints, stains and varnishes

We have also worked for the Trust on eco-renovation of the toilet block, incorporating hot water solar panel system, combined with wood burning stove to heat the toilets and the Trust’s offices.

Woodland College Details

Until we have prepared a downloadable fact sheet, the full design and technical details of the project can be read on the Trust’s web site at: http://www.greenwoodtrust.org.uk/WoodlandCollege.htm

INITIAL CONCEPT

The brief was to design multi purpose spaces and create building using local timber- particularly low grade timber (strong social, economic and environmental arguments for this). With the client group, we expanded the brief to include very high levels of energy efficiency and design with rigorous ecological criteria throughout the building and to involve a local building team.
All products were chosen because in some way they minimised their adverse environmental impact compared to other products. The predominance of timber based products throughout the building illustrates the importance of timber products in sustainable building. Many were made in Scandinavia – but don’t have to be!

COMPLETED DESIGN

The Woodland College is now entering its 21st year of use, and is weathering well. In 2006, an extension to the original building was completed for a new vegetarian cafe and shop selling green wood products. The Woodland Hall is a popular venue, hired out for conferences, meetings, singing workshops, and weddings.

 The building design incorporates the following:

• Modern balloon timber framing, using home-grown local timber
• high thermal mass internally with masonry walls and solid floor
• Full-fill pumped cellulose insulation; 300mm roof and walls
• 150mm eps floor insulation
• good air-tightness detailing
• MVHR ventilation system
• high quality home-grown timber double glazed windows
• low water usage sanitaryware
• On-site reed bed sewage treatment system
• Clean burning wood stoves for space heating
• natural linoleum floor finish
• Natural paints and finishes throughout
• Passive solar design as key to building’s orientation and position
• timber-based roof finish

This building was built with a very modest budget, and with the help of volunteers and non-specialist staff labour. Because of this, we designed it with a very simple plan.  However, the investment the Trust made to commission an unusual timber structure and to pursue the theme of energy efficient alongside ecological healthy materials has reaped its benefits.

Through its use by a huge variety of user groups,  it broadens out the debate about sustainability; as Gerwyn Lewis, commissioning director said ” it is a significant building that gave the whole site a new image, and brought the organisation to the world of sustainable development .”

We continue to work with the client group to look for opportunities to monitor its performance; this is currently being investigated to maintain the Gold Award from the Green Tourism Business Scheme.

BUILDING PERFORMANCE

Peak space heating loads for the building = 5 kW

‘U’ Values W/m2k     External walls 0.16 Ground floor 0.17 Roof 0.13 Vertical windows 1.5 Roof lights 2.0 External doors 0.7 Air infiltration assumed 0.34 air changes per hour; ventilation rate 0.34. Compared to a standard new building that meets the building regulation standards, the insulation levels here are more than 2.5 times higher.Overall, a 70% reduction in  total energy demand (compared to a conventional building) should be possible and an 80% reduction in CO2 emissions (in part due to the use of wood as a heating fuel).

Heat Storage

The internal walls (including the two-storey firewall) are built using dense concrete blocks in order to store heat gained during warmer periods and remain warm into periods of colder weather. the walls act in much the same way as a storage radiator and help maintain temperatures inside the building when temperatures are rising and falling outside.