Record-high prices of energy sources, higher bills for businesses and households as well as more and more visible human impact on carbon emissions and climate change – all of that clearly signals a need for a change in our lifestyle and everyday choices. And maybe even most importantly, it causes the search for energy-saving solutions in the field of construction and joinery purchases. We have to change the way we design, construct and operate our buildings. How to do it? Well, energy-efficient houses seem to be the answer we’re looking for.
An energy-efficient house is generally a building with reduced heating and operating costs. Such constructions use not only renewable energy sources (like e.g. a heat pump or photovoltaic panels), but also the most modern solutions with the best thermal insulation parameters that prevent losses of already produced energy. The world’s leading standard in energy efficient construction is a Passive House, characterised by energy savings as high as 90% compared to conventional standards of new buildings. Passive homes can maintain an almost constant temperature, requiring little energy for heating and avoiding high energy bills. Obviously, passive windows and passive doors have to demonstrate far greater efficiency than conventional widows and doors, too.
What is a passive house?
Established by the Passivhaus Institute in Darmstadt (Germany) in 1996, a Passive House is a concept for building low-energy houses, which are to be less expensive to heat and cool, more comfortable for their inhabitants and more resilient to extreme weather conditions. In other words, a passive home is an affordable and environmentally friendly building, which uses solutions aimed at minimising energy consumption and heat loss during operation. The heating demand in passive houses is below 15 kWh/(m² year) – for standard buildings it is as much as 8 times bigger!
In order to achieve the above mentioned objectives, a house has to be built according to 5 passive house principles. These include:
- High insulation
- Excellent airtightness
- Mechanical Heat Recovery Ventilation (MHRV) system
- No thermal bridging
- High performance windows and doors
All these key principles have to be combined together and impact one another in the passive house design. Below, we will take a closer look at one of these principles, namely passive windows. It is clear that properly selected windows enhance living comfort and help reduce heating costs substantially. That’s why it’s worth getting to know them better!
What windows for a passive house
To be honest, there is no such thing as a passive house window type. The term ‘passive house window’ refers more to the thermal insulation parameters of the window. Naturally, window openings are the most common cause of heat loss in buildings. That is why, when selecting the best windows for a passive house it is important to remember that the heat transfer coefficient, also called U-value, should not exceed 0.8 W/m²K.
Although passive windows don’t have any specific required components or elements, they share some common characteristics. For this reason, when looking for the best U-value windows for your passive house, you should take the following features into consideration:
- Triple-glazed units – triple glazed windows can offer U-Value as low as 0.7W/m2K
- The gaps between the individual glass panes filled with argon or krypton noble gases
- Low-emissivity (low-E) glass – glass with a thin metal oxide coating which improves the window’s thermal performance by reflecting heat into the home (while not affecting the incoming external light)
- Window frames made of low thermal conductivity materials (most preferably, uPVC or wood)
- Thermal breaks within the structural frame – materials incorporated into the frame to prevent conductive thermal energy loss.
- The use of warm edge spacers (thermal spacers)
- High solar energy transmittance – which means that natural heat from the sun’s radiation can be utilised more effectively in order to reduce the annual primary energy requirement
How to locate passive windows in a passive house
Obviously, in order to make the most of energy efficient windows, you have to carefully consider how they are incorporated into the building design. And the requirements for passive house windows will differ worldwide. People living in hot climates will want to reduce solar gain, while those inhabiting cold areas will want to maximise it. Thus, they will choose glazing options and window locations based on the different criteria.
The main feature of passive houses is the appropriate layout of the rooms. For the Northern Hemisphere, the rule is that utility rooms such as the living room, kitchen or living rooms are oriented to the south. This arrangement guarantees the greatest daily exposure to sunlight. In these rooms, large glazing is also used, allowing for increased exposure to sunlight. In the summer, south-facing windows can be shaded by properly chosen blinds and shutters. Windows on the north side are, on the other hand, avoided due to the fact that heat losses are the greatest there.
But whatever your climate, airtight, thermally broken and well-insulated passive windows will maintain steady interior temperatures and comfort regardless of whether you are in a very warm or cold area. The reason is simple: proper insulation effectively reduces the heat exchange between systems with different temperatures. Therefore, it also protects the house interior from gaining heat from the surroundings.
Where to buy passive house windows
Fenbro offers versatile window profile systems that are excellently suited for the passive house standard, based on their innovative frame technology and high quality. What’s important, all our high performance windows are not restricted to installation in passive houses only. Windows complying with the passive house design standard can be used both in renovation projects and in any new building.
The passive windows options to choose from the Fenbro offer:
Energy-efficient uPVC windows
Energy-efficient aluminium windows
How to choose energy-efficient windows for the passive home
Properly selected passive windows with the best U-value mean lower heating bills. The first step to buying the right window solutions is choosing the right passive windows supplier. Competent customer service and a wide range of products will allow you to choose a system that is ideal for your passive home. Obviously, we should remember that even the best passive window will not fully realise its thermal insulation properties if it is not properly installed. That’s why check Fenbro windows and doors fitting services and contact our Sales Team for a free quote on your chosen models of passive windows.