ARTICLE Libby Schultz

If you’re adding new extra rooms as part of your renovation – or changing the use of existing rooms – it’s an ideal opportunity to re-position things for maximum warmth and natural light, with a mid-range budget starting at $20,000.

If you have a slightly larger budget to work with, why not read the high-end warm up home options and prices. Or if you are looking just to get the basic downs, read the basic warm up home options and prices.

Location, location

To capture the afternoon sun, you’ll want the main glazing in your house – including windows, skylights and glass doors – to face north. Anywhere between 20ºW - 30ºE of true north is fine.

East-facing windows get the morning sun; so choose your glazing based on how much heat or shade you want in those rooms. South-facing windows receive minimal sun, so should be relatively small, while still allowing for light and ventilation.

But don’t be too much of a sun-worshipper, warns energy efficiency expert Ella Te Huia.

“It’s possible to have too much glass and too much sun…causing glare and overheating. Anyone who has lived in this situation knows how uncomfortable that can be.”

In particular, you’ll want less glazing facing west, because the late afternoon sun can cause the worst overheating.

“As a rule of thumb, any west or south-facing walls should not have more than 30% glazing.”

Double glazed windows help make your home warmer

Extra-insulated

Should you upgrade your insulation now, or wait till you’re ready to renovate? Our experts say you should make ceiling and floor insulation a priority, regardless of your future renovation plans.

In a non-insulated home, around 40% of heat is lost through the ceiling. Floors account for 10%, but are easier and cheaper to insulate, so are well worth doing.

For everything else, it’s more cost-efficient to tackle as part of your renovation. Exterior walls, which account for around 20% of heat loss, are tricky to retrofit.

Likewise, with windows; it’s easier to install new double-glazing than do a retrofit.

If you really want maximum value from your insulation, Ella Te Huia recommends bumping up the R-value of your ceiling insulation. If you live in warmer areas, the standard insulation is 2.8 – but Ella suggests you upgrade that to 3.2. Similarly, in colder areas, you can add an extra layer of 1.8 to the standard 3.2.

What’s underfoot

Another tip for renovators, says Ella Te Huia, is to supersize your underfloor insulation.

“If you’re building on a concrete slab, some Building Code’s require polystyrene of between 60mm-100mm thickness. But I always recommend to clients to increase that to 150mm…the difference in price is only around 10%, but you’ll reap the benefits.”

If you’re building a timber-framed floor, ask your insulation provider if they offer a high-density or ‘maxi’ version. With these products, the fibres have been compressed together to form a very tight and semi-ridged material.

“High-density might cost around 15% more than standard insulation, but will pay for itself in energy savings within 3-4 years,” says Ella.

Ducted ceiling system in roof cavity used to transfer heat throughout the house

Time to circulate?

Ducted ceiling systems have become popular in recent years – and there are essentially two types.

A ‘heat transfer system’ takes heated air from the living areas, and circulates it to colder parts of the house. It’s best suited to homes that have a wood burner that puts out a lot of extra heat.

Eco Design Adviser Richard Popenhagen says the best heat transfer systems feature insulated duct pipes, and a fan that runs with minimal noise.

A ‘roof space ventilation system’ is something different. It relies on heat forming in the roof cavity, which is then circulated to other rooms in the house. Richard says these systems may not suit every house, particularly if you live in a colder, wet climate.

“If you get a week of cold rain during winter, there may not be any hot air in the ceiling to circulate. Research is showing that, in some cases, they may even be chilling off the house.”

To remove moisture and condensation, says Richard, you may be better off investing in a good extractor fan for the bathroom and a range hood in the kitchen.

Heating costs compared

So you’ve already sorted your energy-efficient room design, insulation, and ventilation. The next big question is: what kind of heating will you choose?

That will depend on both your budget and your personal cosiness preferences. Everyone loves the crackle of a real fire, but are you prepared to lug firewood in every night? And while heat pumps are very convenient, they are hardly a thing of beauty.

In terms of cost to run, however, both those options are front-runners.

Says Richard: “The two cheapest forms of heating are a modern energy-efficient heat pump; or a wood burner, providing you have access to cheap or free firewood.” Most expensive (and unhealthy) of all is an unflued LPG heater.

Reticulated natural gas is the cheapest source of central heating. Or try any plug-in electric heater, such as a fan heater, oil-filled column, radiant panel, or convection heater. 

Renovate Magazine LogoThis home renovation advice article by Libby Shultz featured in Issue 019 of New Zealand Renovate Magazine. New Zealand's first and only magazine solely dedicated to home renovations.

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