What is a Passive House?

Passive House is a fabric-first approach to achieving healthy and comfortable buildings. With up to 90% energy savings for space heating and cooling, Passive Houses use much less energy compared to traditional buildings and even average new buildings. This is achieved through the implementation of passive design measures (such as orientation, building form, solar shadings, etc.) and through building components (such as insulation materials, airtightness layers, heat recovery systems, etc.).

Check out Passive Houses in New ZealandDownload PHINZ brochure

Designing a Passive House

The Passive House standard accurately predicts and delivers a project’s ‘as ­built’ performance. Its success hinges on a robust design process, employing proven methods and on­site verification. Designing a Passive House demands a thorough understanding of energy flows in buildings and the ability to quantify and balance these with a validated tool.

Find a Passive House Professional

Passive House features

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!

The process

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.

See what software is available to you

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.

 

PHINZ stories

Living in a Passive House

Hear about New Zealand Passive Houses, their quality, comfort and energy efficiency, from those who live in one.

Check out Passive Houses in NZ