Passive House Architect: Designing Passive Houses for Central Otago's Climate
Discover how our Passive House design process delivers superior performance and effortless year-round comfort.
What is Passive House Architecture?
Passive House (or PassivHaus) is a low-energy design standard for buildings that minimises energy use while maximising comfort and affordability.
Passive House was created in Germany in the 1980s to hit the sweet spot between creating low-energy buildings, designed to achieve the World Health Organisation recommended temperatures and levels of humidity, at a cost which most people could afford.
There are no specified materials or construction methods, and the buildings are designed specific to the climate region. This means you will have a known outcome in terms of comfort and energy usage, but the design or method of construction is not dictated. This is why it is applicable throughout the world, and can be adapted to suit any type of design or building.
Passive House architecture is designed to retain more heat over time, so less energy is needed to maintain temperature — much like a thermos flask. It creates an airtight, breathable structure to keep warmth in, cold out, and a constant supply of fresh and healthy air. You can expect your building to be at least 20°C in winter and at most 26°C in summer without turning on a fan or a heater. It will also be in a comfortable humidity range of 30-70%.
What 'airtight' means in this context
Airtightness is key to high-performance architecture, and is one of the most misunderstood elements of good building design. Done properly and combined with proper ventilation, it means:
lower energy bills
a consistent and comfortable temperature throughout the whole home
fewer draughts
fresh air constantly cycled through the building
reduced risk of mould and dampness
An airtight home does not mean a sealed box you can't open.
What is involved in designing a Passive House?
Passive House architecture combines the following core principles:
High levels of insulation
Insulated window frames with double or triple glazing
Highly efficient heat recovery ventilation for fresh air
No gaps in the insulation of your home (i.e. no thermal bridge)
An airtight building envelope
Additionally, as part of the design work, we look for ways to reduce your power bill close to zero. We do this by choosing efficient hot water heating and appliances, LED lighting and exploring on-site energy production — for example, solar.
Careful design and detailing combined with a comprehensive understanding of Passive House principles make it possible to construct a home which uses almost no heating and has a fantastic indoor climate. This in turn makes it far easier to create a net zero energy house, because your energy requirements are already extremely low.
What does this mean for you as a homeowner?
In a traditional New Zealand house, and even in many new builds, a substantial amount of heat is lost through the walls, floors and roof. This happens even in what most people would deem to be well-insulated houses. When heat is lost, it has to be replaced, meaning a high energy output and high energy bills.
In a Passive House, heat loss is minimal, and with the use of a combination of passive heating and heat recovery ventilation, almost all of your heating requirements are provided for.
For you, that means a comfortable and healthy living environment with minimal ongoing costs and management. There’s no need to turn heaters on and off, lug firewood around, or keep the log burner stoked.
How much energy does a Passive House consume?
Specific Energy Demand
The Passive House standard has a Specific Energy Demand (heating and cooling) of 15kWh/(m²a).
At Team Green we use Passive House design techniques to create the most efficient buildings we can. Some are designed to reach the Passive House standard, while others still achieve incredibly high levels of energy efficiency while not seeking to reach full certification. Our company-minimum standard for Specific Energy Demand is 50kWh/(m²a).
The table below illustrates heating demand for a three-bedroom house in Queenstown. The site is north-facing, with a lot of solar gain. The table shows how much energy would be required to keep the same building at 20 degrees for the whole year, based on different construction methods.
1 - Passive House
SHD less than 15 kWh/m²a
European timber triple glazed windows
Best-practice insulation and thermal-bridge-free design
Airtightness of 0.5 air changes per hour at 50 pascals pressure. (Note: PH requirement is 0.6 minimum)
2 - TGA Premium
SHD of 25 kWh/m²a
European timber triple-glazed windows
Insulated well above NZ Building Code, minimised thermal bridges
Airtightness of 1.5 air changes per hour at 50 pascals pressure. (In many countries, this is a minimum requirement)
3 - TGA Minimum
SHD of 35 kWh/m²a
Double glazed, thermally broken aluminium windows
Insulated well above NZ Building Code, minimised thermal bridges
Airtightness of 1.5 air changes per hour at 50 pascals pressure. (In many countries, this is a minimum requirement)
4 - NZBC Building Code Minimum
(built after 2007): SHD of 140kWh/m²a
Double glazed aluminium windows
Insulated to current code minimum for South Island, typically numerous thermal bridges
Airtightness of 4 air changes per hour at 50 pascals pressure
5 - Typical NZ home
Typical NZ building in Queenstown built between 1978 and 2007 with a SHD of 285kWh/m²a
Single glazed aluminium windows
Poorly insulated thermal envelope
No meaningful airtightness; significant air leakage
Primary Energy Use
The Passive House standard has a maximum annual Primary Energy Use of 120kWh/(m²a). This is the total energy of all household appliances, and is achieved by reducing the requirement for grid electricity. This can be achieved by using highly efficient hot water heating, LED lighting, and the highest Energy Star rated appliances. This will further reduce your overall energy usage, and therefore costs. You can then look at alternative forms of renewable on-site energy production, such as as solar, which will allow you to much more easily achieve a net zero energy building, bringing your annual energy bill to zero.
How comfortable can I expect to be in a Passive House?
You can expect your building to be comfortable all year round with minimal need for heating. Passive House guidelines suggest you can expect the following:
Operative temperatures* in winter of at least 20°C (throughout the house)
Operative temperature* in summer does not exceed 26°C at 60% Relative Humidity (or equivalent) for more than 5% of the time
Relative Humidity is in a range of 30-70%
Air Velocity is below 0.2m/s
No thermal draft
Ability to adjust hydrothermal conditions to a degree
Frequency of overheating ≤ 10% of the time
* Operative temperature is the mean of the surface temperature and radiant room temperature
Passive House criteria
Maximum Heat Load ≤ 10W/m2
Specific Energy Demand (heating & cooling) ≤ 15kWh/(m²a) (Energy required for space heating or cooling)
Maximum Annual Primary Energy ≤ 120kWh/(m²a)
Airtightness (under pressure of 50 Pascal) n50 ≤ 0.6 per hr
Internal Surface Temperatures ≤ 3°C Below mean ambient Temperature
Thermal Bridges ≤ 0.01 W/(mK)
Ventilation System ≥ 75% efficient
While not all of our projects will achieve these criteria, all of our designs incorporate the principles of Passive House, which means incredible levels of energy efficiency, far exceeding what most NZ homeowners are accustomed to.
Discover more about Passive House
To learn more about Passive House, please explore the resources below.
The BRE Passive House Primer gives a great overview of Passive House
The iPHA brochure is a more detailed document from The Passive House Association
The ProClima study looks into the challenges associated with moisture control and airtightness, and how they can be overcome
LET'S GET STARTED
+64 21 942 985
