Mātauranga | Education
This is a Māori word for education. The idea of this page is to impart some knowledge, wisdom and understanding to the reader, so we all grow together. As I learn, I will share useful information on this page, to help you learn too. The knowledge gained will help us as individual people spread the healthy homes message and ultimately help the health of Aotearoa and the whole planet.
Which Wall Works?
A study in the price of wall framing construction
Negative, Positive, Neither?
A live study of specific ventilation systems.
My passion is creating happy, warm, dry, well ventilated, resilient, healthy homes for all people to live in. I’m working on a multi-year renovation of 3 St Albans townhouses. This has slowed down due to interest rate increases and the time taken to obtain the Code of Compliance Certificate for work already completed. (I have CCC now!) I have convinced myself well and truly now that ventilation cannot be competently controlled by just opening windows. Without very good ventilation, no home can be called a healthyhome.
The next stage is to upgrade the ventilation from being intermittent negative pressure (bathroom fans & range hood) to continuous mechanical ventilation with heat recovery.In the meantime, I thought I could conduct an experiment with a continuous negative pressure system.
What's the potential pathway?
A study in the risk of excessive internal moisture in SIP panel homes
HOW MUCH WILL IT COST?
A STUDY IN THERMAL ENVELOPE PERFORMANCE
When you’re building your dream home, wouldn’t it be super to know that the wall and roof options you chose were the most energy efficient and cost effective for your home?
We’re working on a project where the client asked us to model different wall and window combinations to see which was the most thermally efficient and price competitive for their particular situation. They are based in the lower North Island, in what is Climate Zone 3, under the 2021 H1 amendments.
Four different thermal envelope combinations were modelled against three different window systems and while that was happening, a local builder & quantity surveyor priced ballpark square metre construction rates for each thermal envelope option.
The options chosen were:
Light timber framing – The Superhome Movement’s Superwall (or what MBIE calls a warm wall), consisting of 140mm framing and a 45mm service cavity.
Outsilation – Rigid insulation on the outside like they do in Europe and a warm roof.
SIP Panels – A New Zealand manufactured panel with an expanded polystyrene (EPS) core.
Hybrid – SIP Panels walls combined with a warm roof. (Full construction breakdowns are provided below)
Each thermal envelope was paired with three different New Zealand made window systems.
• A New Zealand wide supplier of aluminium joinery using a “code minimum” thermally broken system.
• A North Island supplier of aluminium joinery that has slightly better performance characteristics.
• A South Island supplier of aluminium joinery, that is being used in passive house construction.
The results were benchmarked against the 2007 H1 Requirements, the 2021 H1 Requirements and the Superhome Movement’s BASE, BETTER, BEST voluntary guidance from their Healthy Home Design Guide.
The outcome is shown in the table below for the heating demand of this particular property.
We found the results very interesting, as on a kWh/(m2a) basis, the thermal envelope systems all look very similar. But remember this needs to be multiplied out for the size of the home. The other factor is that some systems are easier to make airtight than others and go up quicker.
As can be seen from the table above and was noted by the person who provided the prices, it’s the windows specification that provides the biggest bang for buck. Something some of us have been banging on about for quite a while https://www.abodemagazine.co.nz/home/2021/9/3/windows-for-warmth?rq=window, you can now look through for yourselves!
By using the best performing window system your budget can afford, you can clearly see that it is possible to drop your heating demand to nearly a half of that when sitting inside a standard shiny silver shocker!
Further, look at how much better financially you fare, when your power bill comes in, compared with the worst house than can legally be built. (Code Minimum 2021)
So there you have it, facts and figures, not sugar coated, but perhaps wrapped up in some fluffy, or not so fluffy stuff, as the (ply rigid air barrier /bracing layer) case may be.
I have my clear favourite peering through the pinus radiata monoculture, do you?
What is the carbon footprint of each option? That might be the subject of a future article.
In cooperation with
The Webster family
Plan B Architecture
Alan Craig Design
Relationship Between Relative Humidity and Temperature
What is Condensation?
Housing In New Zealand (1946)
Housing In New Zealand (1946)