FAQ’s

What is the difference between Energy Efficient and Passive?

A Passive Home must be certified by a Passive House Certifier. An Energy Efficient Home can be built using the Passive House principles but does not require the certification.


How much does it cost to build a fully Passive House?

The bad news is – it’s not cheap to build a Passive House. You also have the cost of certification. Because the cost is very dependant on the design, it is hard to give an accurate price. As a ballpark figure you can expect to pay around $3000 – $5000 per m2.


How much does it cost to build Energy Efficient?

On average (for a standard 3-4 bedroom home) you would be looking at an additional $70-$80k. We suggest allowing $2400 per m2 to build an Energy Efficient home.


How long does it take to build a Passive / Energy Efficient House?

Every build has it’s own challenges and timeframes are often weather dependant. On average, the build time for an Energy Efficient Home is 5-6 months. Passive Homes take approximately 7 months.


What window system is the most Energy Efficient?

uPVC, tilt & turn, triple glazed windows with low emmisivity coating, argon gas and warm edge spacers are the most Energy Efficient. When we install your window within your insulation layer, their thermal efficiency is further increased.


Do I have to have a Heat Recovery System?

The present Building Code says no, you don’t. However, any house that is built without a Mechanical Ventilation System is a “sick house”. We highly recommend incorporating a HRS in our Energy Efficient Homes. One of the goals when building an Energy Efficient Home is creating an air tight building envelope; without mechanical ventilation, the air in your home will become stale & damp.

HRS also helps with purifying the air within your home and recovering heat energy so your home stays healthy and warm.

Heat Recovery Systems are a requirement of Passive House builds.

You can’t confuse an HRS with the likes HRV & DVS systems. The HRS system is contained within the thermal envelope, not the roof space.


What are the Passive House requirements for Canterbury?

New Zealand is zoned within the warm-temperate classification of Passive Housing.

Your roof must have a U value of 0.2W/(m2K)

Your walls must be U = 0.3W/(m2K) or less.

Your floor must be U = 0.45W/(m2K) or less.

Air changes must be less than 0.6p/h.

Your house then needs to be certified by a Passive House Certifier.


If I want to build Passive / Energy Efficient, what type of site should I purchase?

The perfect site for an Energy Efficient or Passive House should be North – South orrientated, allowing for living towards the North and shelter from the East and West. If you need help decifering what sections could be best for you, get in touch! Our team are happy to help.


I want to build an Energy Efficient Home but my budget is on the smaller side, what add-ons should I incorporate first?

There are 3 key components to make sure you incorporate first:

  1. Upgraded insulation
  2. Upgraded windows
  3. Heat Recovery System

When we are building your house we need to do the things we can not do later.


Does Energy Efficient Homes conduct blower door testing?

Sure do! We have an ATTMA registered blower door tester on our team.


Why isn’t Energy Efficient Homes part of the Super Home Movement?

We are no longer part of the Super Home Movement. We took that decision when the Super Home Movement decided that houses had to be star rated.

The misconception that people have for the Star Rating (and that is encouraged by the Super Home Movement) is that the higher the stars, the higher the Energy Efficiency. When, in fact, the maximum stars awarded for Energy Efficiency is 5/10. The rest are for lifestyle. If you want a vege garden, sort out your rubbish, have a fruit tree, live near the bus stop and recycle your waste water this will give you a greater star rating. It is possible to build a home to the NZ Building Code and make it a 6 star home just by encorporating lifestyle factors.


Can I get my Energy Efficient / Passive House Home Star Rated?

Yes you can! The maximum you will achieve for Energy Efficiency is 5 stars, the additional stars are dependant on your lifestyle choices. Home Star Certification can be arranged on request.


Does Energy Efficient Homes have any association with Whitehouse Builders?

Whitehouse Builders is our sister company; also founded by our Director: Robert Whitehouse. WHB specialise in Affordable Homes, Architectural Homes & Hill Sites. Check out the WHB website here.


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PASSIVE HOUSE TERMINOLOGIES

Air changesAir changes per hour, abbreviated ACPH or ACH, or air change rate is a measure of the air volume added to or removed from a space in one hour, divided by the volume of the space.
Air tightnessBuilding airtightness (also called envelope airtightness) can be defined as the resistance to inward or outward air leakage through unintentional leakage points or areas in the building envelope
Argon gasArgon gas is used to increase the energy efficiency and general performance of thermal windows. Argon is an inexpensive, non-toxic, colorless, and odorless gas that occurs naturally and constitutes less than 1 percent of Earth’s atmosphere.
ATTMAAir Tightness Testing and Measurement Association. Learn more.
Blower door testblower door test is used on buildings in order to quantify the amount of air leakage through its enclosure. During this test, a calibrated fan is installed in an otherwise sealed door or window, while all the other openings to the exterior are closed.
Building envelopebuilding envelope is the physical separator between the conditioned and unconditioned environment of a building including the resistance to air, water, heat, light, and noise transfer.
Carbon footprintCarbon footprint is defined as the amount of carbon dioxide released into the atmosphere as a result of the activities of a particular individual, organization, or community.
DehumidificationDehumidification is the removal of vapor from a gas-vapor mixture. In the processing of materials it is often necessary to reduce the amount of vapor present in a gas stream, a process referred to as dehumidification. In dehumidification, partial condensation must be effected and the condensed vapor removed.
EmissionsCar exhaust, burps, and radio broadcasts are all examples of emissions. Technically, an emission is anything that’s been released out into the open. But more often it refers to gases being released into the air, like greenhouse gasses or emissions from power plants and factories.
Energy efficientEnergy efficiency simply means using less energy to perform the same task – that is, eliminating energy waste. Energy efficiency brings a variety of benefits: reducing greenhouse gas emissions, reducing demand for energy imports, and lowering our costs on a household and economy-wide level.
EPS polystyreneExpanded PolyStyrene (EPS) is a white foam plastic material produced from solid beads of polystyrene. It is primarily used for packaging, insulation etc. It is a closed cell, rigid foam material.
G valuesTotal solar transmittance, proportion of the solar energy available for the room.
Heat exchangerAn air-to-air heat exchanger brings two air streams of different temperatures into thermal contact, transferring heat from the exhausting inside air to incoming outside air during the heating season.
Heat transfer coefficient (U value)Thermal transmittance, also known as Uvalue, is the rate of transfer of heat through a structure (which can be a single material or a composite), divided by the difference in temperature across that structure. The units of measurement are W/m²K. The better-insulated a structure is, the lower the Uvalue will be.
Home StarsHomestar is a holistic tool that to rate a home’s performance and environmental impact. A 10 Homestar rating recognises world leading standards for design, construction and efficiency in operation. A 6 Homestar rating recognises a home that has been built at or above the current standards set by the New Zealand building code, dependent on location across Aotearoa. Learn more.
Insulation layerThe layer within your building envelope that holds the insulation and acts against thermal bridges.
Krypton gasKryton Gas is sometimes used instead of/alongside Argon gas inside your windows. These gasses are dense, and so they impede the transfer of outside cold to a warm house better than air.
Low – E coatingLow Emittance, or Low E, is a razor-thin, colorless, non-toxic coating applied to window glass to improve energy efficiency.
PascalsPascals can be abbreviated as Pa; for example, 1 pascal can be written as 1 Pa. Pressure in pascals is equal to the force in newtons divided by the area in square meters.
PassiveThe strategy of a Passive House is to reuse “free” heat to heat the home. “Free” heat is generated from all electrical and gas appliances such ovens, refrigerators, computers and light bulbs.
Passive House CertifiedA house that has been Certified to meet Passive House Standards as set by the PassivHaus Institut.
Passive House Planning Package (PHPP)The Passive House Planning Package (PHPP) (order here) contains everything necessary for designing a properly functioning Passive House. The PHPP prepares an energy balance and calculates the annual energy demand of the building based on the user input relating to the building’s characteristics.
Passive House PrinciplesThere are 5 Passive House Principles.
1. Quality Insulation
2. Upgraded Windows
3. Air tightness
4. Mechanical Ventilation
5. Thermal bridge free design
Passive Trades CertifiedA Certified Passive Tradesperson must pass the Passive House Trades Exam, prove their work on Energy Efficient builds and Passive Builds as well as maintain training by earning “points” and renewing their license.
Passive House InstituteThe Passive House Institute New Zealand (PHINZ) is an Incorporated Charitable Trust. Their mission is to increase the awareness of the benefits and opportunities of high-performance buildings based on the Passive House Standard, through research, education and building industry engagement.
R valueThe thermal resistance rating or RValue is the measure used most commonly in the building and construction industry to determine a material’s ability to resist the transfer of heat. The higher the RValue the better thermal resistance the product will provide. Units: m2K/W.
Renewable primary energy demandWe estimate that total global use of renewable energy will rise by about 1% in 2021. Despite supply chain disruptions that have paused or delayed activity in several key regions, the expansion of solar, wind and hydro power is expected to help renewable electricity generation to rise by nearly 5% in 2021.
Solar transmittanceSolar transmittance (τe) and solar reflectance (ρe) refer to the ratio of the radiant flux of solar energy vertically incident on a glass surface to the transmitted radiant flux or reflected radiant flux.
Space cooling energy demandSpace cooling demand. The amount of active cooling input required to cool a building usually expressed in kWh/m2/yr. It is often calculated using building energy software applications such as PHPP, Deap or Sap.
Space heating energy demandSpace heating demand. The amount of active heating input required to heat a building usually expressed in kWh/m2/yr. It is often calculated using building energy software applications such as PHPP, Deap or Sap.
Super Home MovementThe Superhome Movement is an industry-led group focused on creating transformative change in the New Zealand building industry. The movement provides a number of key activities centred around education and lobbying to support change in the New Zealand building industry.
Thermal bridgingthermal bridge, also called a cold bridge, is an area of a building construction which has a significantly higher heat transfer than the surrounding materials.
Thermal comfortThermal comfort is important for health and well-being as well as productivity. A lack of thermal comfort causes stress among building occupants. When they are too warm, people can feel tired; when too cold, they will be restless and distracted.
Thermal efficiencyThe thermal efficiency of a heat engine is the percentage of heat energy that is transformed into work. Thermal efficiency is defined as. The efficiency of even the best heat engines is low; usually below 50% and often far below.
Thermal insulationThermal insulation is a relatively simple solution that seeks to prevent too much heat loss and too much heat gain. Some of the most common areas to insulate include lofts, cavity walls, external walls, and floors.
Warm edge spacerswarm edge spacer is a type of spacer bar used in insulated glazing. It separates the panes of glass in double or triple glazing, or curtain walling and seals off the air cavity between each. Recent warm edge spacers are generally made from plastics, although stainless steel can meet the definition.
World green building councilThe World Green Building Council (WorldGBC) is a non-profit organisation and global network of national Green Building Councils (GBCs). It has member councils in over 70 countries worldwide, which collectively have 49,000 members (25,000 member companies and 24,000 individual members).
XPS polystyreneExpanded Polystyrene, referred to as XPS, is a closed cell insulation product commonly used in remodeling and new construction applications. Due to the manufacturing process, XPS insulation is typically available only in standard dimension square or rectangular boards.