You can now take courses and sit the exam to become a Certified Passive House Designer in New Zealand.
Unitec is offering an introductory course in June (ARCH8623), followed by extensive exam preparation in November (ARCH8625).
To enrol in this classes go to the enrolment form.
This website has more information on the qualification that you may gain after passing the exam. Be aware: the exam is rather challenging, so there is no guarantee for passing - this is a serious certificate!

Check out the new Passive House Wiki.
You can help filling in the missing terms and links by registering in the Wiki space - please follow the instructions there.

Often, mechanical ventilation is excluded from considerations for energy efficient buildings as it consumes energy. It does. However: let us put this in perspective. A very efficient heat recovery ventilation system can have an energy load as low as 38 Watt (W) for a 125 square meter house. Assuming, the system is running on 200 days per year (24h), 182 kilowatt-hours (kWh) electricity are consumed. Efficient systems in Germany were measured! as having an average coefficient of performance (COP) of 16.5. For every kWh electrical energy consumed, 16.5 kWh heat were delivered. Compare this with the stated! COP of a heat pump!
But there is another interesting comparison. Electric blankets have an energy load of ca. 100W. Let us assume one blanket is used at 180 days per year for 8 hours: 144 kWh are consumed – to keep one person warm. As soon as another person in the household needs a blanket, the whole-house heat recovery ventilation system consumes less energy, while not only providing fresh air on 200 days in the year, but also doing most of the heating - at least in a well insulated and airtight building - keeping everyone warm 24/7! In addition, the system can also filter out noise and pollutants, and you do not have to worry about someone taking advantage of your open windows, when you are trying to get rid of excess moisture. Heat recovery systems proven to be highly energy efficient (via a 3rd party certification), are however currently not on the market in NZ. Or are they? My research in this regard was unsuccessful – but I would be pleased to hear otherwise!
Picture thanks to Qurren, under the GNU Free Documentation License.

Students at the University of Auckland were required to design details for Passive Houses in New Zealand climates in scale 1:1, plus: they actually had to build them! Here is an example of a window detail in a timber frame wall:


The challenge was to minimize thermal bridges and safeguard airtightness of all joints. Needless to say that the construction also had to be weathertight.




Design by Lin Ma.

Passive Houses do well in lifecycle analyses, as a range of recent research shows (please email me for references). Thus, it is nonsensical when some people demand not to build to Passive House standard on grounds that this leads to admittedly (slightly) higher embodied energy values than for a conventional building using the same principal construction method. Insulation - due to its light weight, typically only slightly impacts on the embodied energy balance of a house. When you are concerned about embodied energy, considering a timber building rather than building with concrete or steel will have much larger consequences than additional 10cm of insulation.
Another factor in this discussion that is often overlooked: Embodied energy in buildings is not lost, but largely only stored for future usage. Many parts of old buildings are already re-used, without much further energy input. Considering a growing resource scarcity, this will almost certainly lead to an increased asset stripping rather than simply putting demolition rubble on a landfill. Today's buildings can become tomorrow's hardware shops. Fossil fuels burnt today to heat houses, though, cannot be burnt again in the foreseeable future.
Picture courtesy of Markus Schweiss, protected under GNU Free Documentation License.

On 17 and 18 April, 100 speakers from around the world will convene at the 13th International Passive House Conference in Frankfurt/Germany, to present and discuss new trends, products and developments around passive housing. The conference will examine implementation of the Passive House concept in places like Korea, USA, Spain, Slovakia and many Scandinavian countries. As always, there is an accompanying exhibition, showcasing the latest in Passive Housed technology. See www passivhaustagung.de for more.

A forum was added to this website. It is intended as an exchange and debating tool for professionals. Everyone is free to look things up, but this is NOT the place to obtain general information about Passive Houses. Please continue to use the Questions? Comments? Button for this purpose instead.
All building professionals are cordially invited to register and join the discussion!

For inexplicable reasons a doctrine of preferring “natural” ventilation prevails in NZ. Funny though, hardly anyone advocates “natural” laundry practices – for good reasons: a (washing) machine can do the job more efficiently, conveniently and environmentally friendly. Same goes for ventilation. “Naturally” ventilated buildings are usually either under- or over ventilated; additionally, there is no way to re-use the warmth of the outgoing air. As natural ventilation relies on weather and stack effects, it is impossible to control airways or amounts of air exchanged. Much like throwing your laundry in the river, and picking it up 2-3 km downstream, hoping that nature has sufficiently tumbled and spun the load.
Please note: mechanical heat recovery ventilation is not air conditioning; air is always fresh - not reused; you can open windows and doors as you please; fine tune to your hearts content; switch the system on and off as you wish. It is – unlike most mechanical ventilation systems on the market in NZ - a balanced system, meaning: there is no pressure differential between indoors and outdoors. A well designed system is silent, too, and can filter pollutants, allergens, and noise.
Yes, mechanical ventilation uses energy - but efficient systems need very little electrical energy to do a good job - plus true heat recovery models regain thermal energy from outgoing air, thus saving energy for heating the fresh air.
In cars, it is long understood that a mechanical ventilation system gives far better control of the in-car environment, than just relying on opening windows. In fact, I sometimes jump to the conclusion that New Zealanders are spending that much time in their cars, because there – unlike in their homes – they are able to maintain comfortable climate conditions. In a Passive House with mechanical heat recovery ventilation the comforts of home can truly be experienced; if this leads to a reduced recourse to the car – the better!

In Auckland, you probably would not have wanted to live in a house that relies solely on solar gains to be warm in recent weeks, because sunshine hours were rather rare. I take this as an occasion to make a distinction between Passive Solar schemes and Passive Houses:

Passive Solar	Passive House
Specific insolation requirements	Works with minimal solar gains (e.g. southern orientation)
Additional thermal mass requirements	Does not need additional thermal mass
Needs favourable weather conditions to be comfortable	Is comfortable year round
Provides solar gains predominantly during spring and fall	No heating requirements during spring and fall
Relies on natural forces for ventilation	Uses controlled mechanical ventilation
Design principles are widely promoted	Clearly defined and proven concept

Achieving a good indoor-outdoor flow is generally desirable for a residential building. Yet, when indoors and outdoors are not sufficiently separated, it is impossible to condition the indoors efficiently. You need a lot of energy to keep the interior of a sieve in a thermal state different from its environment.
There most definitely has to be an air exchange between inside and outside, and this really is a matter of survival. However: it is nearly impossible to construct a house with involuntary openings, i.e. air gaps in just the right way to provide optimum ventilation regardless of outdoor conditions. Thus, while they are not airtight, average houses are usually not at all well ventilated. Humidity and insufficient oxygen supply are a result. And this is where the circle closes: a precondition for efficient ventilation is reliable airtightness of the building envelope. Without it, airways and ventilation effects are uncontrollable.
Nothing prevents you from opening windows and doors in an airtight building. It’s just: only in an airtight building can you use windows and doors – or an efficient heat recovery ventilation system, to control in- and exfiltration. The added bonus is that noise and six legged friends will be bared from entering as well – unless you open a door or window for them!

When designing highly energy efficient buildings, every last bit of performance counts. R-values as customary given in NZ are unsuitable to provide detailed information about the thermal performance of an insulation layer in this regard. R-values are usually derived values: nominal thickness of the layer (in m), divided by thermal conductivity of the specific material (in W/(m K)). The result of this calculation is – according to International Standard 6946 - expressed with at least 3 digits after the dot, but this is reduced to only one digit in NZ product ratings.
Let’s say for insulation layer A, the calculatory R-value is: 0.950 m²K/W, and for insulation layer B: 1.049 m²K/W – under rounding rules, both get an R-value rating of 1.0 (usually, no unit is given in publications when R-values are mentioned in NZ).
With the same rating, there is a difference in performance of 9.9% – let’s do some rounding ourselves here and make that 10%.
With just the R-value stated, this uncertainty is concealed from the consumer. While the uncertainty margin shrinks with growing R-values, it still remains totally unclear, why essential values are not stated, and a broad brush approach is taken instead.
Countries that do take energy efficiency in the building sector seriously, i.e. all of Europe, including the UK, do not use R-values as the measure of thermal performance, but use thermal conductivity as a clear and unambiguous indicator. If the thermal conductivity and layer thickness for a product is known, the R-value can easily be established by simple division – due to rounding, however, this doesn’t work the other way around. For loose fill insulation products, R-values are impractical in any case, as the layers thickness will conform to e.g. an existing cavity - not any arbitrary thickness stated on the product's documentation. But even with blanket type products: if product A has a thickness of 8 cm, with an R-value of 2.0, and product B a thickness of 86 mm, with an R-value of 2.1 - it isn't easy to figure out the better of the two!
Thermal conductivity is given with 3 digits after the dot, which makes it very easy to compare performance of products (e.g. mineral wool might come in a range of 0.032-0.045 W/(m K)). At one glance it is obvious, which is the product with the best thermal performance.
The thermal conductivity of materials is not easily obtainable in NZ, yet many a little matters, when thresholds need to be met. To build better buildings, better information is an essential precondition, which makes all the difference between planning and guessing. Especially with Passive Houses, there is no half way. Either you are comfortable without a heating system – or you are not. There is no room here for large margins of uncertainty, in particular if they are easily preventable. To all manufacturers of insulation material: show us your thermal conductivities!

While you do not need a fireplace in a Passive House to keep warm, sometimes even building physicists like to be romantic and gaze at a flame. So, if you don’t mind the extra money, why not install a fireplace in your Passive House? Of course you need a clean, highly efficient system, but that is not enough.
To operate a fireplace safely in a Passive House, 4 conditions must be met:
1. The fireplace must be ventilated independently (external air supply)
2. The whole system (fireplace/flues) must be airtight
3. A flap valve in the flue must prevent back drafts
4. A differential pressure switch must switch off the ventilation system, if large pressure differentials exist (in case of a malfunction).
Without these safeguards in place, there is a risk of suffocation when fires are operated in conjunction with a ventilation system.

Check here for an example that meets condition 1 and 2 (sorry, German only):

Zero Energy Buildings are all the rage. But what does it really mean and is it worth aiming for?

If “zero“ refers to heating energy – a Passive House needs almost zero, but stops shortly before the big naught, for a reason: the last mile on the road to zero is by far the most expensive! In terms of comfort there are no additional benefits of zero energy houses compared to ultra low energy houses, like Passive Houses. While I would never want to wreck someone’s ambitions to take the last step, in terms of saved kWh per invested money it is not the most sensible thing to do.
The main ingredient of Passive Houses is insulation, insulation and more insulation. Unlike most high-tech solutions, insulation has a very high life expectancy, ongoing savings without the need for regular maintenance, and unparalleled comfort benefits. In addition, insulation is a comparatively cheap building material. It is less sexy, though and will not raise anyone’s pulse. But it is the smart thing to do. If after heavily investing in the best possible insulation measures and a highly efficient ventilation system there is still some money in your bank account – you can always try to go all the way. The additional benefits for yourself and the environment will be minimal, though.

If “zero” however means to be completely independent of external energy supply, and all energy required to run the house has to be produced by or within the house itself, zero energy houses create energy islands. This, too, comes at a hefty price. Of course it is in most cases a lot less expensive to participate on an energy grid (except in very remote areas), rather than to try and produce all energy by your own means.
If funds are plentiful and do not compromise other investments in efficient energy use (e.g. still allow buying an efficient vehicle), this is all very well.
But is it worth aspiring to? Not in my opinion. Networks are the beacons of civilisation. Especially when more unsteady renewable energy sources (like wind and solar) are harvested, the grid plays a valuable role as a buffer zone. Therefore, I am all in favour of linked-up energy supply, and believe the money spent on energy islands can be put to better use elsewhere.
It is, however, easily possible to turn an ultra efficient building into a zero emission house: the remaining energy demand can be covered by a supplier who only uses renewable resources, like e.g. Meridian Energy. Smaller, privately or collectively owned networks are another alternative.

With a tradition of seriously underheated, uncomfortable houses in New Zealand, moderate insulation levels will not save any heating energy. Room temperatures will go up instead – which is good, because current indoor temperatures are at an unhealthy and inconvenient level. However, to save energy in the domestic sector, insulation levels must be considerably higher to surmount the threshold of saturated demand for healthier and cosier indoors.
The new Building Code levels of insulation will lead to increased indoor temperatures, and better and healthier homes. Yet, anyone serious about saving energy must go considerable lengths beyond the mandatory levels.
The Passive House standard provides a comfortable and healthy indoors AND saves energy, even compared to the current underheated and unhealthy average consumption. 15 kWh per square meter and annum is the Passive House benchmark. It is regularly reached in much harsher climate conditions than those that can be found in NZ. You can have both with Passive Houses: Warm and healthy homes, and serious energy savings.