Unheated Houses

[Peter Berry]

Hi folks, I've been lurking for a month or so, learning more about NZ.

I've read a lot about cold houses in NZ, the problem being a lack or even an absence of insulation.

What about the opposite? Are there many houses that are so well insulated that they don't need heated at all? How about getting one built? Are there builders who could do this?

Solar in the UK is a problem because of the lack of winter sunshine, which NZ doesn't seem to suffer from nearly as badly.

Any and all tips, thoughts, advice and experiences welcome.

Peter

[tigerlily]

Hi Peter, welcome!

I guess you could build a super insulated house (and great cost no doubt). But even though it's much more sunny here than the UK we do have cloudy days, so solar alone (even with massive insulation) wouldn't keep you warm all winter. Certainly the far north is closer to tropical, and you could have something like a wood stove (ideally with ducting to circulate warm air to other rooms) as back up.

We have 2 heat pumps at opposite ends of our house. I think all rooms are toasty, except the toilet!

I hear houses built into the side of a hill are at a constant comfortable temperature. Maybe hobbits had the right idea.

[kiwieagle]

Have a look around here: http://ecobob.co.nz
It's called passive solar design.

[Beachcombers]

I think it is perfectly possible to build a house that requires minimal energy input, there is a number of technologies available now in NZ which should not cost a massive premium over the cost of a "standard" house build.

We always wanted to ship a kit set house from Sweden/Finland (triple glazing, 1 meter thick insulation).

[Familyofmonkeys]

Part of the problem here is availability of better performing insulation products. You cannot actually source many of the standard products used in the UK/Europe/North America from within NZ and would need to import them, at huge personal financial cost. The products that are available on the market within NZ have a lower R value compared to commonly used products within the UK, which I'm using as a comparison because the climate is more similar to NZ than continental Europe, Scandinavia or N America. For example, we did a UK garage conversion back in 2005 and the insualtion board we used (readily available from DIY shops) has nearly twice the R value compared to the same thickenss of Pink Batts in NZ.

Another issue you'll come across is building quality. I have seen first hand how badly (i.e. slap-dash) methods NZ builder use when laying insulation under the slab or insulating around the foundation slab. I also watched both my previous UK homes being built, and much more care was taken. That is not to say you cannot get the job done properly in NZ if you were getting a house built, but it would be prudent to watch every step of the build like a hawk. You can't rectify many bad jobs retrospectively.

The Ecobob website is a good place to start, but bear in mind much of the technology and building methods being used are relatively dated and behind the times when compared to the eco homes now being built elsewhere in the world. You will rarely see things like triple glazing here, for example, and they are very fond of stuffing wool insulation in the walls for insulation. Whilst this is certainly an ecologically sound approach, there are FAR better performing insualtion products available which also last considerably longer and will reduce your energy consumption more. Passive solar designs are talked about a great deal in NZ, but they are only going to be as effective as the insualtion and windows used to keep the heat in. They also frequently neglect to consider how a house design will block out high angled summer sunlight, and instead put silly windows in high places to let the heat out....which will also let the heat out in winter!!

[Super_BQ]

I completely agree with NZ's lack of insulation products (more or less, the choice of building materials in NZ is small and outdated). The problem is testing of new building materials to meet NZ's climate and standards is very costly.

Before I go into detail, it's good to know that the bulk of NZ's population live in the N. Island and of those living there, the larger % live in the Auckland region. The design requirements to build a low carbon footprint house in the S. Island is almost a world apart than building in Auckland due to the difference in climate.

If you have Facebook, this person built a super insulated house based under German's Passive Haus certificate scheme (a 1st in NZ): https://www.facebook.com/passivehousenz

Despite having great detail to air tightness and all, the passive house certification does not mean zero heating requirement because for the days where there's no sun (overcast and raining) for many days in winter months, supplemental heating will be required. The particular house was built near Hamilton and having 6kWh per sqm heating requirement / (their house was blower tested having 0.47 air changes per hour).

Quite interestingly NZ local testing authority BRANZ did a review on passive house building and they had some very interesting comments in their latest magazine: http://www.branz.co.nz/elements/build/133/build.html#81

They basically concluded that to build under passive haus approach is not warranted (or perhaps wasteful or too easy) for mild climates in NZ (particularly Auckland region). At a 20 - 30% increase in cost of standard builds (for Auckland region), you will find that almost every home owner would prefer the 3 or 4 bedroom home instead of a 2 or 3 bedroom home. If it costs $500K to build a 4 bedroom house in Auckland, would one pay $650K for same # of bedrooms but having low heating requirements? (after all, $150,000 can buy you a lot of electricity for heating). This is the reason why most passive haus houses are small as it's easier to meet energy targets - unfortunately, small does not suit the typical kiwi family. To build passive haus requirements in Christchurch would simply be unaffordable.

It is also very important to clarify that such passive haus building approach is entirely different to current NZ building code requirements (that fall under the breathable wall category of construction). So 30% extra in cost to build is an understatement because builders in NZ have no experience in this kind of detail (achieving draft free air tight construction). Whereas in colder places like Canada and in Europe, where a building industry has always followed air tight construction, the extra cost to build passive haus would be negligible.

Passive solar has a major problem that not every house has maximum positioning towards the sun. Some sections in a sub-division or in a valley may get very little sun.

[Dell]

My Auckland cousin told me not to consider a house that isn't north-facing.

[nativecolo]

I have no knowledge of this field but I have been told that the newer areas being developed have better insulated houses since they follow current building regulations. Example cited being Aotea in Wellington from what I remember.

[Super_BQ]

In new sub-divisions factoring restrictions on recession planes by local council, the concept of a 'north facing' lot is of less importance. The only issue where lots don't get much sun is if they're situated deep in a valley or hill side or next to a 2 story house that is too close to them. So apart from those concerns, pretty much all newly sub-divided lots will still receive decent amount of sun and it's the role of the builder / architect to make best use of the house orientation as it fits on the lot. However people are different in their living habits inside the house.

Some prefer their master bedroom to see the early morning such and the garage to get the bulk of the north facing sun and then by evening, the kitchen sees the sun. I have preference for the kitchen to be in the north facing getting early morning sun and then to late afternoon. The best house layouts are one that gets maximum sun at all times of the day so that there's a balance of solar heat throughout the whole house, vs zoning particular rooms to get maximum north facing sun while the rest of the house stays cold. I'm looking up and down my street and it appears the garages are all situated close to the front part of the house closest to the street with no regard if it's north or south facing, so we can assume that convenience is still the #1 choice in the layout of the house.

If you want the maximum sun, pick a corner section lot and build 2 story.

[bulu]

My living/kitchen gets the morning sun while my bedrooms only get the evening sun. During winter mornings, I would quickly get to the living/kitchen area as that area could be up to 5 degrees warmer than the bedrooms. Then in the evenings, the bedrooms would get warmer.

My neighbour's house on the other hand has only their bedrooms facing north while their living/kitchen facing south - which is pretty cold. They tell me they have to put on their heaters all the time, or otherwise they will just stay in their bedrooms.