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22 August 2018

Renovation Opportunity and R-Values

miguel bruna 653087 unsplash

In the previous article, ‘Achieving Winter Warmth in New Zealand homes’, I made claims about house performance for renovations — making homes easier to heat. In this article, I’m tackling real-estate adverts, renovation by paint, and discussing one area of cost for whole-house renovation and the connection between health and wealth.

If you’ve ever heard the term ‘Resene Renovation’ or ‘Dulux do-up’ hopefully you’ll understand the target. The target of criticism is not the paint company, it’s the renovator who thought that covering up a mess with paint could be called a renovation. We’ve all seen the adverts “Renovated to a high standard” where the only work was a bathroom tidy-up and a paint job.  The net result is a sale for some extra dollars but the same level of performance (low) and outcome (poor) as before. True renovation is a very infrequent opportunity to improve the building, not just the visible skin.

Beyond this ‘paint renovation’ is a similar claim in advertisements stating ‘fully renovated’, which usually means there has been insulation put in the ceiling and under the floor. What the advert might more accurately state is: “Fully insulated where we could easily reach”.

So what is my beef with this? Well, it certainly is not against insulation, but we should all be for insulation being installed with purpose. One of the websites for Brits looking to emigrate to New Zealand has some pretty embarrassing statements about the state of the homes immigrants can expect to live in here. It warns:

If you’ve bought a garden shed masquerading as a family home, you can insulate it, double-glaze it and install central-heating to make it equivalent to a home in another developed country. It will cost plenty of money, but until you’ve lived (and frozen) in one of these old New Zealand houses, you can’t truly appreciate the value of these improvements.” (8 Must-Knows, ENZ).

So, how should we address this? 

Insulating, double glazing and installing heating/ventilation systems. Of course, these do not come for free, but then neither does healthcare and we have one of the highest rates of respiratory illness… but I digress. We promote deliberate airtightness with the use of Smart Vapour Retarders (ours is called INTELLO) and this costs money. So let’s balance some costs. If ‘better insulation’ means choosing a higher R-value product, that sounds good, but it might not have the expected gain (or bang for buck).

Let’s consider the insulation cost for a 90mm stud wall:

  • R2.6 costs approx $11/m² retail
  • R2.8 costs approx $17/m² retail
  • The cost difference is around $6/m² but the performance gain is only around R0.1 (yes, that is rough performance maths)

Why twice the price? The density increase means using ‘twice the amount of fibre’. The shipping costs increase because the higher density product does not compress nearly as much (volume is therefore higher). And it’s slower to install because it is harder to cut and fit accurately. Ultimately the gain in performance (R0.1) is not worth it. So how do we gain performance of insulation? By enclosing it fully with airtightness membranes or products. 

  • R2.8 + air leaking through might result in real performance of R2.0 or less
  • R2.6 + air leaking through might result in real performance of R2.0 or less
  • R2.6 with airtightness = R2.6 (with reduction due to framing members if insulation is installed between studs)

Doing this step is likely to be close to cost neutral with $17/m² but with performance improvements due to still air in the insulation (so R2.6 behaves like R2.6 in the test lab) and the control of internal air volume — it is unable to bleed out through gaps and cracks in the envelope.

So what am I promoting? Fix the performance of the shell of the building. A nice Resene paint job is great if the envelope of the building is working well.

To put interventions in a priority order, the last thing to consider might be PV (photovoltaic) panels. “[Consider PV panels] when the initial load is reduced.” (

Wealth gain from renovation

Renovation work is an infrequent opportunity to improve the health outcomes of occupants, and health is wealth. Health is wealth monetarily, socially and spiritually. Being at work and not at home sick or looking after sick children is wealth — wealth in earnings, advancement and social connection. Funnily enough, it’s good for children to be at school for their future earnings, advancement and social connections.

Health is wealth in capacity for engagement with community groups — church, arts and sports for example. Funnily enough, it’s good for our mental wellbeing too.

“Health is not everything, but without health, everything is nothing,” Arthur Schopenhauer (1788-1860)

Please visit us in Penrose at our showroom and training centre to see how to renovate with measurable results. Visit the Pro Clima Hub website for details of events including ‘bring your plans’ on Thursday mornings from 9-11am.

View more information on Pro Clima, including contact details.
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