Achieving Zero Energy and providing a comfortable and healthy environment for visitors year-round were the drivers behind the design of the building envelope for Camp Glenorchy Eco Retreat’s cabins and communal buildings. The envelope plays a key role in the performance of any building. The roof, walls and ground slab, as well as the windows and doors, work together to keep the people inside comfortable and healthy. In addition to providing shelter, this physical barrier helps regulate indoor temperature and controls both moisture and airflow.
The solution chosen for Camp Glenorchy, which strikes a balance between comfort and energy efficiency, resulted from a collaborative design process guided by an evolving thermal model. Effort during this process focused on two key areas: regulating indoor temperature and controlling unwanted airflow. In practical terms this meant identifying the right level of insulation for the different elements of the envelope – a process aided by the thermal model’s results – and including details that would reduce unwanted air flow. As a result of this exercise, the envelope of Camp Glenorchy’s buildings uses up to 60% more insulation than that required by the New Zealand Building Code.
Cabins and bunk huts at Camp Glenorchy combine two different wall-construction systems. While these are typically used separately, at Camp Glenorchy they work together to create super-insulated external walls and skillion roofs. The two systems are:
Cabins and bunk huts also incorporate elements aimed at reducing unwanted airflow and moisture. INTELLO® PLUS, a smart membrane that acts as an air-tightness barrier and vapour control layer is installed in the interior of buildings. This continuous film sits between the timber frame and the lining of walls and roofs, protecting the buildings from condensation and draughts. In addition to the INTELLO® PLUS membrane, cabins at Camp Glenorchy have a weathertightness underlay (or building wrap) adhered to the exterior of the SIPs and use weathertightness tape in the joints between panels and around windows. This is done to prevent air or water from leaking into the envelope.
Windows are typically one of the weak spots of a building envelope, allowing the highest transfer of heat between the inside and the outside. To reduce the speed at which heat is lost in the winter, Camp Glenorchy’s windows are triple-glazed and use timber frames, which offer better thermal performance than aluminium frames. Between glass panes, the presence of argon gas acts as an additional barrier to heat loss and increases the performance of the windows by up to 15%. Also, a ‘Low Emissivity’ (Low-E) coating maximises solar heat gain in winter by reflecting heat back into the rooms.
Insulated concrete floors not only provide a platform for Camp Glenorchy’s buildings to rest on, but are the medium used to deliver warmth to rooms in the winter through a water-based underfloor heating system. To improve their performance, these concrete floors use polystyrene in a grid of pods laid underneath the slab, as well as around the slab’s edges. Having better insulated slabs keeps the temperature of the slab stable and prevents the heat loss that typically occurs around the edges. It also maximises the benefits of the heating system by preventing the hot water that flows through its pipes from cooling down too quickly, thus saving precious energy.
While the design phase of any project offers the best opportunities for improving the performance of buildings, the quality of workmanship during construction will also have a major impact. Unwanted air flowing through the building envelope can create condensation and lower the wall’s construction R-value (thermal insulation rating), affecting both indoor air quality and energy efficiency. The draftier the building, the harder the heating system will need to work to keep indoor temperatures stable. At Camp Glenorchy, an increase of 5% in the energy used for heating caused by unwanted drafts could make all the difference in achieving the Zero Energy goal.
To prevent this from happening, airtightness was checked at multiple stages during construction. In the Homestead building, for example, testing for airtightness was done in three stages:
Now that Camp Glenorchy is open to the public, efforts made around the quality of the building envelope during design and construction are being put to the test by guests and staff. So far, Camp Glenorchy’s buildings are performing as expected. High levels of insulation, good airtightness and good ventilation are working together to create buildings that are healthy and comfortable year round.
It’s warm even when it’s frosty outside. And it is an all-round heat – there aren’t any cold spots.
“Guests often comment on how cosy and warm it feels in the Homestead building,” says Ann Margaret from Camp Glenorchy’s host services. “It’s warm even when it’s frosty outside. And it is an all-round heat – there aren’t any cold spots.”
Got any questions you want us to answer in the article?
Or use the same button to subscribe and find out when the article is released.