What is a Passive House? Should You Consider Building One?
At a time where energy efficiency has assumed utmost significance especially in building & construction, the concept of a passive house could not have aged at the right time. If you are planning to build an extension or are building a new house, you may want to consider updating your house to a passive house and save huge on your energy bills.
While building standards may be a novel concept, their roots go a long way back and are actually not as novel as we may assume them to be. While the building regulations standard did come into force during the late 1960s, its next evolution, which is the future homes standard, has just started to stamp its first steps. But what came in the late 17th & early 18th century was an invention that in today’s context is no short of a revolution.
Energy efficiency has been the most talked about concept lately when it comes to building & construction. The building regulation standard and the recently evolving future homes standard have been playing a pivotal role towards achieving energy efficiency & better insulation for residences across the UK. But what most of them may not know is that the concept of achieving better insulation standards to attain energy efficient homes was an outcome of resource shortages and natural calamities that drove the necessity for invention in the late 17th century.
Yes, outcomes such as shortage of wood, and deforestation that resulted in timber crisis compelled homeowners in Iceland to look towards other means. Turf houses, characterised by flat stones and wooden frames on the top, offered superior insulation from cold climates. Insulation methods continued to evolve with the first form of a passive house being realised in the form of a polar ship in 1893.
Passive House as Homes
The gradual evolution of insulated homes in the form of a passive house evolved to suit the modern era, with the first experiment done in Copenhagen in Denmark, where the first zero-energy house was constructed. This was followed by initiatives in Germany, North America, and to many other parts of the globe where passive house development continued to gain momentum and expansion.
Let’s now delve into the details of what makes a passive house and whether you should build one for yourself.
What is a Passive House?
It’s all about the construction. A passive house is a construction methodology that is engineered and detailed in such a way that it requires minimal energy usage for heating or cooling purposes.
A passive house is considered to be the leading standard for all energy efficient constructions ensuring the highest energy efficiency, comfort, and quality of living.
Is there a Standard for a Passive House?
Yes, a passive house is based on a design standard to ensure high quality, energy efficient homes. They are designed as a whole house approach that uses high quality fabric & windows, with a controlled ventilation offering heat recovery and an optimal comfort.
The structural orientation is such that the house remains cooler in summer and warmer in winter. They are characterised by external shading and overhangs which help achieve this extraordinary convenience even for rooms that are exposed to extreme temperature changes.
Passive houses are certified by the Passivhaus Institute, which offers quality assurance with all buildings undergoing rigorous quality testing and compliance, even for specific components of the construction.
The key features are summarised as follows –
- High insulation levels at every nook and corner of the building, including walls, roofs, floors, and windows to prevent any amount of heat loss.
- Airtight building construction is achieved through meticulous sealing of all gaps and cracks, thus reducing air infiltration.
- Mechanical ventilation system with extremely efficient heat recovery that provides constant fresh air inside the building. This system is designed to recover lost heat from exhaust and thus helps in maintaining a comfortable indoor temperature and reduces energy consumption.
- ‘Thermal bridge free’ construction – which means that high thermal conductivity is ensured, that allows for seamless heat transfer. These are maintained by adopting superior insulation means that restrict the formation of a thermal bridge.
- Extremely high-performance windows with well insulated frames achieved through triple-glazed windows made of high-quality materials. They are placed such that the gaps between each pane is sealed with special gaseous elements such as argon and krypton.
- Accurate design modelling in line with the passive house standards
Living in a passive house is truly a feeling of living in an extremely light and fresh environment. Typically, passive houses have beautiful open spaces all around and accentuate the elated feeling of living inside regardless of which part of the house you are in.
One of the reasons why living in a passive house makes for a comfortable experience is because of the air quality. Passive houses have great air quality with a renewed feeling every day of living in the house. Though like any other normal house, a passive house depends on the atmospheric air outside, but what makes it stand out is how the air is borrowed externally.
Essential Components of a Passive House Construction
- Air-tight membrane
- Triple glazed windows
- Mechanical Ventilation & Heat Recovery (MHVR)
- Thermal Insulation
One can easily come under the impression that the passive house standard is designed only for the new builds. Thanks to the process of construction, adoption, and design principles.
Contrary to the perception, existing houses can also be retrofitted to a passive house standard in the form of an extension or a conversion. While the process of retrofitting, though can be a demanding and complex process, it is undoubtedly a highly rewarding outcome.
Converting an Existing House into a Passive House Standard
Although applying passive house standards & principles to a new build is much easier, retrofitting an existing house to a passive house standard will significantly reduce energy consumption. This means lower energy bills whilst providing a highly comfortable & sustainable living experience. Having said that, a passive house retrofit for an existing house may not attain the same insulation levels as that of a new build.
Let’s look at a few considerations one should keep in mind when retrofitting an existing house to passive house standards –
1. Site Survey
Conducting a site survey helps you in determining the viability of the retrofit. This is important especially when installing MVHR systems, glazed windows, and other insulative components to your existing property. Planning the ductwork will be critical to ensure an efficient insulation and ventilation system.
2. Hire Professionals
As passive house retrofits are complex adaptations and require careful planning & considerations, hiring structural engineers or architects before you decide to convert your existing house is crucial. Professionals like structural engineers are the only qualified people who can guide on the viability of the project. They can also in fact help you get a cost estimate that can illustrate the feasibility of it.
3. Get an Energy Audit Done
A thorough energy audit of your house helps in assessing your home’s energy performance and identifying areas that require energy improvements. This is helpful especially when considering installing insulation, air sealants, and other ventilation components.
4. Consider Upgrading
Once you are through with the audit, choose insulation components and materials that offer high thermal performance. For example, aluminium, uPVC, and some form of timber can be considered. Many of these materials in the form of windows are highly durable and are resistant to external atmospheric weather and temperature.
Though your professional will guide as to what to do in the next course of time, it is better to know your future course of action. Once the audit is done and you have identified areas that require an upgrade, you can now start applying passive house standards to your existing building.
Adding insulation layers to walls, floors, & roofs, upgrading to triple glazed windows, sealing gaps or cracks to prevent warm air from escaping all are part of the standard that require action.
Consider choosing sustainable building materials, reclaimed materials that reduce the carbon footprint for retrofitting.
5. Get it Certified
Once you are done converting your house into a passive house, you can then seek to get the house certified by a recognised passive house certification institute or a body.
Cost of Upgrading to Passive House Standards
Building a passive house UK requires thoughtful planning to ensure you stay within the budget. Numerous factors such as quality & type of materials, location of the property, and design complexity, all play a crucial role in deciding the costs.
If you are applying passive house standards to a new build in 2025, the cost may range from £1,300 to £2,700 per sq mtre.
If you are retrofitting your existing house to passive house standards, the cost may range from £500 to £1000 per sq mtre.
Conclusion
If you are planning for a new build, this is the opportunity to consider a passive house. Not only do they offer a high quality & healthy living experience, but they also elevate the quality and standard of your living for a long long time. With so much importance towards energy efficient living, passive houses are arguably a blessing in disguise for those desiring a sustainable environment and an energy efficient living.
If you too are planning for upgrading your house to passive house standards or want to build new, you have got the right experts at your disposal. Experts at Extension Architecture are specialists in offering guidance and helping execute many such energy efficient projects for a sustainable living. Contact us now!
