There’s a bit of an issue in Stewart Island. Not the sort of problem we’d ever been faced with before at InsideOut, but when our client rang to find out how much to use and what to do about the penguins, the cogs started ticking. The floor slab of the planned Rakiura Museum and Heritage Centre was about to be put to work.
It seemed likely that the lack of opposable thumbs would mean that using polyisocyanurate insulation would scupper the plans of our feathered friends, but how much and where? Of course it never makes sense to only concentrate on one aspect of a design without looking at the knock on benefits and risks.
The trust needs to be able to operate the building over the years on a tight budget and that meant a building which worked well for itself with the minimum of fuel hungry systems. By the time we had thought through what the indoor environment needed to be for comfort and function, and modelled the project spaces and their interactions we had some specification recommendations.
Hot water underfloor heating was already planned for the project meaning insulation would need to be beneath the pipework. The earlier design for the slab was thicker than necessary for structural requirements and finding the appropriate depth for efficient thermal mass saved 1/3 of the concrete costs providing a floor which would be warm in winter and keep things cool in summer. A big saving when all materials must be shipped to the island.
Running with the theme of savings, the underfloor heating could be served by a diesel boiler, avoiding using electricity costing 60c per unit to generate. It was even possible that used shipping oil from the cruise ships bringing visitors to the island could be utilised in place of diesel with some adaptation to the boiler. Further fuel could be saved using a solar hot water system which also reduced the energy required for domestic hot water.
Because the value of the museum rests on its ability to protect the artefacts on display it had been thought that a dehumidification system that could be delivered as part of an HVAC design would be necessary. Using the modelling to take a look, it seemed that the naturally occurring relative humidity levels would actually be quite acceptable for the items that were envisaged. For small and delicate artefacts which might find their way into the collection in the future, sealed, moisture controlled cases were thought to be sufficient.
With the extension of the heated floor across the building and its thermal mass dealing with any overheating it was possible to open up the prospect that a traditional heating, ventilating and cooling system might make way for a simpler tempered fresh air system with heat recovery. This could be particularly energy resourceful in combination with our proposed natural ventilation pathway for the museum.
Daylight was considered important to the aesthetic and feel of the space and a large skylight was a part of the design. Looking at light levels allowed us to propose reducing its size which had a secondary impact of a saving on the heating energy required inside.
The energy savings were further supported by addressing the levels of insulation in the building’s external enclosure. Adequately insulating the walls, adding a warm roof and going for low emissivity glazing provided a well thought out building envelope.
So from a simple concern about penguins we helped find capital cost and resource savings and continuing efficiencies. The design was warm enough, cool enough, light enough, and airy enough for our occupants and the precious artefacts.
The heritage centre is not quite built yet as the funding for such projects can take a considerable time to acquire. We look forward to visiting one day and seeing the bewildered penguins and the museum for ourselves.
In the mean time we would like to thank Opus Architecture for bringing the project to our attention and accepting our pro bono response to all their questions and more.
If you would like to support the building of this amazing resource yourself, please visit http://www.rakiuramuseum.co.nz/Our-sponsors.aspx and make a donation. I’m sure it would be gratefully received.
