PASSIVE HOUSE EXPLAINED
What is a Passive House Standard?
Passive House is a rigorous, performance-based, energy-efficiency construction standard.
It consistently and predictably provides a high level of comfort, even in the most extreme weather conditions.
Passive House is the highest energy efficiency standard for buildings in the world.
The Passive House approach is suitable for buildings in any climate zone.
While it radically reduces household energy consumption, the design and construction principles underlying it are based on solid science.
What is a Passive House, and how does it work?
A building designed according to Passive House standards completely separates the indoor environment from the outdoors. Homes built to the Passive House standard use a building envelope's first approach consisting of insulation, air sealing, and no thermal bridging. Windows, doors, and other penetrations in the building envelope are all extremely high-performing and explicitly tailored to the site and local climate.
A Passive House is oriented to best take advantage of the sun's energy for heating in the winter and shade in the summer. Temperatures inside the home stay comfortable between 20 and 25 degrees C, despite the outside conditions and temperatures fluctuate significantly. The Passive House approach allows you to achieve excellent control of your environment while also drastically cutting your energy bills and reducing your environmental footprint.
Passive House buildings rely primarily on 'passive' influences such as sunshine, shade and ventilation to achieve comfortable temperatures rather than air conditioning and heating. Mechanical ventilation ensures the continuous flow of fresh, filtered air into your living spaces while energy harvesting and heat recovery keep internal temperatures comfortable.
There are certification levels within the Passive House Standard. A building that achieves Passive House Plus certification is net-zero. One built to Passive House Premium will be net-positive energy usage. All Passive Houses will reach around a 90% reduction in space heating and cooling demand than the current code minimum. There is also a Passive House certification program for retrofits called EnerPHit. These upgrades have reduced homeowners' energy usage by up to 93%!
Passive House offers the opportunity for homes to be resilient, healthy, economical, and environmentally friendly. They protect the homeowner from rising energy costs and extreme weather conditions. They also provide a very high comfort level throughout the year and superb indoor air quality due to the continuous provision of fresh, filtered air throughout the home. In addition, we eliminate cold spots and the potential for condensation and surface mould growth by eliminating thermal bridges. All assemblies of the building envelope are model tested for thermal and humidity movement; thus, any possibility of condensation and mould growth inside the walls or roof is eliminated, ensuring the long life expectancy of the house. Passive Houses have a significant "feel good" factor by dramatically reducing your home's environmental impact.
While Passive House originated in Europe, it is suitable for any climate zone. Those healthy, comfortable, and energy-efficient homes have been built and are being built across the world and in Australia like.
Any building can be built to the Passive House Standard - from schools to apartment buildings, community centres, shops, factories, and offices.
PASSIVE HOUSE PRINCIPLES
Principles and Criteria The Passive House standard is based on five principles that have been derived from scientific laws of building physics and include:
• Continuously insulated envelope
• Airtight envelope
• Thermally broken envelope
• Mechanical ventilation with heat recovery
• High-performance components - windows and doors
The benchmarks of the Passive House standard form the underlying reason for these five simple principles. For example, it would not be possible to achieve the operational energy target of 15kWh/(m2a) and maintain a comfortable year-round temperature and good air quality without integrating all principles in a building.
• Principle 1 - Continuously insulated envelope
Passive house design starts with continuous, super insulation around the building's entire shell, insulating the slab, walls, and roof.
• Principle 2 - Airtight envelope
The Passive House standard focuses on creating an airtight building envelope and sealing any potential air leaks through the envelope, around external doors and windows, electrical outlets and pipes that penetrate exterior walls. It is the least costly principle when designed and specified correctly.
Airtightness helps stop heat loss, but it will also help reduce moisture accumulation or loss in cold months/climates. Passive homes are not only more energy-efficient than conventional homes, but they are also the most comfortable and healthy homes available. This high comfort stems from the lack of cold spots, drafts, and interior surfaces where condensation can occur. Improving indoor air quality by stopping moisture accumulation is one way to achieve this.
• Principle 3 - Thermally broken envelope
The concept of Thermal Bridge free design is crucial to the construction of Passive House buildings. Thermal Bridges are areas or breaks in the building envelope that are thermally vulnerable and result in energy loss through heat losses. Lower interior temperatures in the surrounding areas will result from heat losses through thermal bridges. The moisture build-up and mould growth brought on by these lower temperatures impact the health of the occupants and the building's structural integrity.
The windows of the home are perhaps the most crucial consideration for thermal bridges in building design. In Australia, windows have often been thin and single-glazed, encouraging heat escape from the inside to the outside (condensation on windows). Thermally broken multi-glazed windows offer greater performance through insulation, minimising heat losses.
Thermal bridges can also include ceiling junctions, balconies, corners, roof ridges and eaves. Therefore, thermal bridges must be considered, and a higher level of thermal protection must be added during the design phase.
• Principle 4 - Mechanical ventilation with heat or energy recovery
With an airtight enclosure, continuous, balanced ventilation is critical to indoor air quality . Passive House buildings may be naturally ventilated; however, Passive House buildings use a simple, mechanical ventilation system with heat or energy recovery. Passive House buildings continually exhaust stale air from bathrooms, kitchens and areas with stale air and supply fresh air to living and working spaces. A mechanical ventilation system is a simple, low-energy setup with fans that drive air across a heat exchanger. The heat exchanger transfers the heat energy of outgoing air to the incoming air, ensuring that the outdoor air enters the building at approximately the same temperature as the outgoing air. In winter, this pre-heats the incoming air; in summer, heat is rejected back to the outdoors.
• Principle 5 - High-performance components - Windows and Doors
A Passive House must have high-performance windows and doors to meet the airtightness criteria. In order to manage the quantity of solar heat input in winter and reduce undesired heat gain in summer, they must also be precisely sized, positioned, and shaded. The windows must be very well sealed and double or triple-glazed, depending on the climate. The use of double or triple glazing and thermally broken frames reduces the heat flow outwards in winter and inwards in summer. It also reduces the risk of condensation forming on the inside of the glass or frames.
FAQ's ABOUT PASSIVE HOUSE
Can You Open Windows in a Passive House?
In a Passive House, drafts and cold spots are nonexistent, even near windows and doors. And yes, despite the importance of maintaining a robust thermal envelope, you can open windows in a Passive House just like any other building. However, you may find that you do not need to open windows often since the indoor temperature will be very comfortable with continuous filtered fresh air year-round.
Does a Passive House Need Heating/Cooling?
A significant benefit to a Passive House is the minimal energy required to heat/cool a home due to the insulation and tight thermal envelope. A Passive House offers resilience, even when the power goes out. Passive Houses only need a smaller and simpler system, such mini-split heat pump.
Does a Passive House Need a Ventilation System?
Yes. A driving principle behind Passive House is a healthy indoor environment. Through minimal controlled ventilation, high-quality indoor air quality can be achieved. A ventilation unit with heat recovery features is recommended to meet the requirements of a Passive House. If you live in a location with harsh weather conditions, you will undoubtedly need a ventilation system with heat recovery.
Does a Passive House Cost More?
The upfront capital cost to build a Passive House may be slightly higher than a conventional home, but that can be minimised by optimising the design - like using locally available conventional materials put together in a new way that works with Passive House and that the trades are familiar with, by making designs buildable so any good builder can build a Passive House as long as they are willing to learn a few new things.
The significant reduction, or even elimination, of heating and air-conditioning systems, decreases energy bills, saves space and reduces construction costs. These savings are invested in building envelope upgrades. The durability of a certified Passive House and assurance of the quality control of the design and build ensures lower maintenance costs and a long life expectancy of the house.
This upfront capital cost will often be financed in your mortgage, resulting in slightly higher monthly premiums. However, these will be offset by lowered utility costs for the 50-100+ year life of the home. This combination can mean lower monthly costs overall. Passive House certification eliminates the need to engage a thermal assessor – thus taking that expense out of the overall cost and, in many cases, saving money on mortgages. Some banks are already offering smaller interest rates on lending money to build a Passive House home.
Another advantage of the Passive House comes at a resale time when it gives certainty to a buyer that the building has been designed to a PH standard and, more importantly, built correctly.
Additional advantages such as the health, well-being, and comfort measures brought by the strict build quality cannot be easily quantified.
A Passive House is marginally more expensive to build but less costly overall than a conventional home.
If you can afford to build a new house, you can afford to build one in which you will thrive living.
We love the simplicity and straightforward nature of the Passive House principles. They are useful and easy to understand for homeowners looking to improve their homes' energy efficiency, health and comfort.
What Is the Difference Between Passive House and Passive Solar Design?
When deep-diving into the Passive House certification, you may come across terms that are used interchangeably, like "passive design," "solar design," and "passive solar design." While buildings built to Passive House standards use passive solar design principles, there is one primary difference. Passive House uses software based on physics, building science, and thermodynamics to accurately predict the building's actual performance. It uses strict performance metrics to ensure comfort and energy savings.
A home built using passive solar design can be high-performing, but results will vary and won't be possible to fine-tune, and as a consequence, able to extract maximum performance with the least investment. These homes can often require more active involvement from their occupants. This engagement would include closing windows on cold and hot days and opening windows in the evening for the built-up heat to escape.
Passive House Buildings are
Flexible
Passive House design principles can be applied to any domestic or commercial building, from the most humble home to the tallest skyscraper. The approach allows for extraordinary flexibility around building size, shape and materials.
Comfortable
Passive House construction techniques deliver a stable, liveable band of temperatures throughout the year, keeping occupants comfortable in all seasons. In addition, the combination of insulation and ventilation allows for noise-controlled, airy living spaces.
Controllable
The Passive House approach allows homeowners to tailor their environment to their needs – and moods. You have the flexibility to open up the House to enjoy the morning birdsong or shut things down to keep out noise from neighbours or bushfire smoke.
Healthy
Poorly ventilated spaces can sap occupants' energy and promote the spread of dampness, mould and mildew. Therefore, a vital aspect of the Passive House approach is continuous ventilation which circulates oxygen, energises occupants, and helps eliminate toxins and spores.
Sustainable
Most modern houses use far more energy than is necessary. As a result, the world's buildings account for some 39 per cent of CO2 emissions. The Passive Houses approach reduces the energy required for a comfortable home environment by up to 90 per cent.
Affordable
For a bit of upfront investment, you will make your home healthy, comfortable, sustainable, cheap, or free to run.
Happy Birthday, Passive House!
Passive House is celebrating its 30th birthday this year! Starting as an experiment, great credit can be given to this pioneering project by Professor Wolfgang Feist: at a time when only very few people thought about climate protection, it paved the way for energy efficiency in buildings. Today, the Passive House Standard has been implemented throughout the world and shines particularly brightly in beacon projects globally.