Passive House Institute New Zealand

Passive House is a fabric-first approach to achieving healthy and comfortable buildings. A clearly defined standard and a quality management system that produces buildings that deliver on all aspects of occupant well-being while consuming very little energy. There is no longer a need to burn fossil fuels to power the spaces where we live, work and play!

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Orientation and Shading
While Passive House projects are not dependent on solar gains to achieve thermal comfort and energy efficiency, they still benefit from careful consideration of the impact of sun paths and shading. The aim is to ensure that any solar gains will make a positive contribution towards meeting Passive House targets without the risk of overheating.

Form Factor
The complexity of a building’s thermal envelope can have a significant effect on the insulation levels required to meet the Passive House standard. Firstly, a larger thermal envelope will transmit more heat per usable area, and secondly, a complex shape will involve more junctions that create difficulty and cost. Keep it simple!

Insulation and Thermal Bridges
In a Passive House, all components of the building envelope must be well-insulated. Insulation comes in numerous forms, from batts to straw bales, from SIP panels to vacuum panels, and the choice of the material and its thickness depend on the local climate. In addition, all edges, corners, connections and penetrations must be planned with special attention in order to avoid thermal bridges.

Windows and doors
High-performance windows and doors are arguably the single most important component to get right in any Passive House project. Passive House certified windows are available in a number of different frame materials that satisfy strict criteria on thermal performance and airtightness.

Airtightness
Airtightness is central to attaining Passive House certification, but, most importantly, it is a key indicator of construction quality. Remember: a leaky building is not necessarily a breathable building and an airtight building is not automatically bad at managing moisture. Designers need to understand the interaction and independence of these mechanisms when planning, in order to have an airtight building with a healthy indoor environment and a robust, ‘breathable’ thermal envelope.

Ventilation
While a well­-designed thermal envelope is key for achieving thermal comfort, getting the ventilation right is similarly important for feeling cosy and fresh inside. Mechanical ventilation is not mandated by the Passive House standard, but it is the easiest way to meet the energy goals in hot and cool climates, and a precondition for reliable indoor air quality in all climates.

Hot Water & Heating
Heating systems in Passive House projects are generally a lot smaller than people expect! There are many different options available: small heat pumps, direct electric or conventional boilers. Oversizing the heating system can be a waste of money and efficiency. You need very little heat in a Passive House, so keep the heating system small, efficient, responsive and simple!

Software that works
The Passive House Planning Package (PHPP) is the ‘Swiss army knife’ of Passive House modeling and design. It enables designers to assess the impact of design changes accurately and instantaneously. While extra care needs to be taken to safeguard Passive House performance, the steps required to successfully design a Passive House project align closely with those required for any project.

Getting certified: The only way to be sure!
Passive Houses are designed and built according to quantifiable, science-based criteria: a set of minimum performance requirement for attaining the certification according to the Passive House Standard. The certification is third-party and it guarantees achievement of the high-performance-and-quality standard.

There are two options for certification: ‘Certified Passive House Building’, for new constructions, and ‘EnerPHit Retrofits’, for buildings refurbished to the Passive House Institute (PHI) retrofit standard.

Is Passive House just for houses?
The Passive House standard can and has been applied to all buildings that accommodate people: apartments, offices, schools, universities, leisure centres, museums, hospitals and prisons have been certified already.

Whenever it is important to deliver good indoor environmental quality, certified Passive Houses are the best answer!

Aren’t Passive Houses a bit over the top for our mild climate?
No – here is why: Passive Houses are designed specifically for the climate they are built in. As an example, a Passive House in Sweden will need about 40 cm of insulation in the walls, whereas in Auckland, you may get away with a quarter of this, if all other aspects are favourable. Any building has to be modelled accurately within its location and shading situation to get the appropriate response: demonstrated excellent performance.

What about simply opening windows? I thought they were banned under the Passive House standard!
This is a common misconception. Passive House projects are designed to provide good indoor air quality regardless of external conditions and occupancy. High or low outdoor temperatures, more or less wind, noise, outdoor air pollution and occupancy patterns mean that window opening regimes seldom deliver required ventilation rates. Air temperature, humidity and CO2 levels all suffer as a result. Nonetheless, Passive Houses have windows, which can be opened and closed whenever you wish, without compromising fresh air, unlike in a standard house.

Who can design and build a Passive House?
Achieving the Passive House standard is not difficult in principle, but it does require knowledge and planning. The best way to become competent in all things about Passive Housing is to gain a Passive House qualification and then to build Passive Houses!
Certified Passive House Designers or Consultants often have a design background, so if an architect or architectural designer is not yet appointed to the project, perhaps consider an architect/designer who is also a Certified Passive House Designer or Consultant. Passive House Consultants may also have an engineering background and can help with challenges there as well.
Certified Passive House Tradespersons are trained to translate a Passive House design into built reality. All Certified Passive House Professionals have passed a very demanding examination.
Find a Certified Passive House Professional

What is a Low Energy Building?
For starters, it’s not a Passive House. Why then is the Passive House Institute certifying them? In a nutshell, a few years ago they bowed to pressure from the community. Passive House is an all-or-nothing business: you either get there, or you don’t. Designers and consultants were tired of being confronted with the frustrations of home-owners who went through a process, only to narrowly miss a target in the end, and then having nothing to show for it.

On this background, Low Energy certification was created. There was a fear that this will lead to confusion, as people will be unable to make the distinction. On the flip-side, it was argued that Low Energy Buildings – if they are certified – were using the same processes as Passive Houses, and would still be great buildings deserving of some sort of medal. They are – but they are not Passive Houses – the choice is yours!

The PHI building certification guide has more on the differences of the standards.

I still have questions!
Download our comprehensive brochure or drop us a line and we’ll do our best to help you out.