It is incredibly easy to focus all your attention and energy on the products and materials that are going to construct your new home. However one of the most important items for ensuring a warm, comfortable and energy efficient home is the passive solar design.
In fact good design is the most cost-effective component in achieving an energy efficient home. Changing your design part-way through a build can very be costly and sometimes things have progressed too far to allow you to change the design at all. It is therefore incredibly important to ensure that the design of the dwelling has been thought through comprehensively during the concept design and building consent phases.
Original house layout (by us)
Intermediate house layout (by us)
The Design Process
Determining the brief
One of the most important things to articulate early on in the design process is the brief (or your goals). For most houses the goals are around liveable areas and the aesthetics of the building. We had those too but for us our most important goal was to achieve Living Building Challenge certification. This then came with a whole lot of other inherent goals such as Net Zero Energy and Net Zero Water.
Integrating the design process
Once our goals were established we then needed to find a team who would be willing to work with us to achieve those goals.
We were very lucky to secure the services of award winning Architect Phil Smith from Collingridge and Smith Architects. The services of a good architect who understands sustainability is invaluable when it comes to designing a high performing house. Especially since currently in NZ houses are still being designed with garages facing North and all the bedrooms facing South.
We were also lucky to secure the services of Alex Reiche from the Building Excellence Group and Yariv Edney from YEH Consulting who came on board to provide sustainability advice and solar engineering (respectively).
It is often the case that engineers are brought in after the building envelope has been specified by the architects to meet the liveable space requirements of the client. The engineers are then forced to work within the constraints of that envelope to try and make the building perform.
Rather than working sequentially with, first, the architects, and then the engineers, we used an integrated design approach with all parties working in parallel right from the beginning, integrating building performance into the design.
New houses are usually designed with a focus size and liveable area. The current goal seems to be to make it as big as possible within the allowance of the local council's district plan. However a larger house will not perform as well as a smaller one as bigger spaces require more heating.
With an energy target there may be a degree of balancing building size vs. energy performance. The Zero Energy House shaved 8m2 off the building during design which saved enough money for them to pay for both their solar hot water and PV systems. This shows that sometimes less is more.
For us working with our architect Phil has enabled us to take the 396m2 house that we had designed ourselves that included a cantilevered deck that was going to be shading the kids bedrooms downstairs and transform it to an intermediate design of only 366.8m2 . At $3500/m2 that is a $105,000 saving.
In addition to the above there is no second storey above the Minor Household Unit (or self contained flat) which gives us the flexibility to build the main house and then decide as we are going whether or not we can afford to build the MHU.
This design was then modified further by Phil Smith to again rationalise the size and space allocations. Phil convinced us to remove the 3rd garage to further compact the design of the house. He also advised us to try and eliminate having the deck 'hover' above a conditioned space above due to waterproofing concerns. Phil's design actually called for the entire deck to be cantilevered off the eastern side of the house. However we had to compromise a little bit to fit everything in as we are constrained by a required distance from the raised ETS beds (onsite waste water treatment) to the house. So we needed to pull the the house in a little bit to fit it all on the site.
Living BIG in a smaller house
Final house layout
Concept architect's house layout