KDG is a design-led practice with a long track record in Australia and Ireland. We have become recognised as specialists in passive house design over the last few years.

The Passivhaus standard is the most rigorous, science-based energy efficiency standard in the world. Achieving a certified Passivhaus requires much more than building to code.

Kellett Design Group provide Passive House Consultancy services to this stringent international standard.

At Kellett Design Group, we understand that every project has its own specific set of challenges and opportunities, so we offer comprehensive services from start to finish.

We have worked on over 30 projects to date in Ireland and Perth.

The Passivhaus Institut in Germany endorses KDG to certify Passive House buildings internationally.

We design and build high-performance homes to the highest standards of energy efficiency.

Whether you are interested in Passive House Certification or want to create a healthier, more comfortable home, we will help you achieve your goals.

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What is a passive house?

The most common type of passive house is called Passivhaus. This standard was developed by Dr Wolfgang Feistel, who published his first book on the subject in 1993. He later founded the International Passive House Institute, which has become the world leader in promoting sustainable architecture. In 2006, IPHI launched the PassivHaus Standard, which sets strict guidelines for installing insulation in new residential constructions.

A passive house is an energy-efficient building that uses less than 20% of the energy used by conventional structures. It’s also known as a net-zero or zero fuel home and can be built in any climate zone.

The main components are:

  • High-performance windows with low emissivity glass
  • Thermal mass on all surfaces
  • Tight construction for maximum insulation efficiency
  • Airtightness to reduce infiltration losses
  • Extensive use of earth-sheltered design

Passive house explained

The key idea behind passive housing is to slow down heat transfer through your home so that you don’t need to spend money on cooling bills. In other words, instead of using fans and AC units to control the temperature inside your home, passive houses rely on natural convection currents within the envelope itself.

The basic concept of passive housing is based on three principles:

Kellett Design Group - Passive House



Passive houses are insulated well enough to maintain comfortable temperatures year-round without relying on mechanical means like furnaces or air conditioning. Thermal mass refers to the ability of a material to absorb and store large amounts of heat before releasing them slowly into surrounding spaces. Concrete floors, thick brick walls, stone countertops, heavy drapes, and even carpeted flooring are examples of thermal masses.



Airflow is another important factor when designing a passive house. Natural convection currents help move hot air out of living areas and replace it with fresh air. Windows should allow plenty of cross breezes to enter the home. If there aren’t adequate openings, then exhaust fans will be needed to remove stale indoor air.



Tightly sealed structures limit the amount of heat transferred between indoors and outdoors. Waterproofing membranes prevent water intrusion and provide an additional barrier for keeping out pests. Double pane windows can also significantly cut energy loss.

Our passion is to provide Passive House Consultancy services to this stringent international standard.

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Some FAQs About Passive Housing

What’s the difference between a passive house and a green building?

Green buildings focus more on environmental sustainability than just energy efficiency. They often include features like low VOC paints, recycled content products, and sustainable landscaping practices. However, these types of projects usually come at a premium price tag.

How much does a passive house cost?

Passive houses typically have higher initial costs because they require extra materials such as concrete walls, special foundation designs, heating systems, ventilation systems, waterproofing membranes, geothermal heat pumps, etc — but those added expenses pay off very quickly! A new passive house could save $100/month over 30 years if its occupants do not make significant repairs to their homes.

Passive house building material

– exterior wall cladding
– allows solar gain while reducing U value. It helps keep the interior cool during the summer months and warm during the winter months.
– double glazing
– reduces the transmittance of both visible light and infrared radiation from entering the space. This makes rooms feel more relaxed in summer and warmer in winter.
– roof shingle system
– provides excellent long term maintenance
– free protection against water penetration and wear due to snow loads and wind uplift forces
– rain screen membrane
– protects the structure below from moisture damage caused by precipitation accumulation above the membrane

Passive house roofing systems

The most common type of roofing system used in passive houses is called TPO. The advantage of this material over other types of roofs such as asphalt shingles is its ability to withstand extreme weather conditions like heavy winds and hail storms without leaking. In addition, there is no need for painting which saves money and time.

Passive house windows

The window frame must have at least two layers of glass separated by one layer of polyethylene sheeting. There should not be more than 1/8″ gap between each pane of glass. If you live in a cold area where temperatures drop well below freezing, consider adding additional layers of polyethylene film around your windows.

Passive house products 

– doors
– skylights
– ventilation
– heating & cooling
– lighting
– appliances
– plumbing
– electrical
– floor coverings

Passive house ventilation design

The best way to achieve good indoor air quality is through proper ventilation. Passive houses have very little fresh air exchange because they rely heavily on natural convection currents. Therefore, when designing a passive house, you must consider how much fresh air needs to enter your home each day. You should aim to have about 10 times more fresh air per person inside the house than what would typically be found outside.

Passive house heating system

A passive house heating system uses electricity only to run pumps that circulate heated water throughout the house. The circulation process creates a continuous cycle of transferring heat from one area to another. There are two types of systems used in passive homes; hydronic and radiant. Hydronic systems have been around since the early 1900s. Still, they were not widely adopted until recently because they required expensive plumbing fixtures and piping.

Passive house heat recovery ventilation

To achieve high levels of comfort in a building, it’s necessary to ensure good airflow across all surfaces. Achieving this requires careful planning at every stage of construction. One way to do this is to use what is known as ‘heat recovery ventilation. HRVs work by drawing warm outdoor air into the building via vents located near the top of each window frame. As the air passes over cold glass panes, some of its warmth is lost.

Passive house modelling software

This simulation tool allows users to create detailed 3D models of buildings and their components such as HVAC equipment, lighting, appliances, furniture, etc., and simulate performance under different conditions. It provides information about the total annual consumption of electrical power, fuel oil, gas, steam, chilled water, space heating, and cooling.