Design Process
Passivhaus-certified buildings
We often talk about the Passivhaus certification from the perspective of designing newly built single-family homes. This time, however, we would like to take a different approach, highlighting its relevance in the world of multi-family housing as well.
This is the case with Passivhaus-certified buildings.
Although it may seem challenging, with an upfront investment and a solid design and project approach, it is entirely possible to achieve Passivhaus-certified buildings, provided they meet the parameters of this certification in terms of overall energy consumption.
In this article, we will explain how to build Passivhaus-certified buildings and also introduce two useful tools to view built examples that can inspire us or reassure us that it is feasible—and a sound investment—to consider multi-family housing built to these standards.
Passivhaus Certification – What is it?
Let us begin by briefly recalling what the Passivhaus certificate or seal is.
The Passivhaus seal is a German certification that measures and classifies the level of passivity of a house or building.
Passivhaus-certified buildings, therefore, are those that meet specific requirements in terms of heating and energy consumption.
A Passivhaus home must meet certain criteria based on passive-architecture construction strategies and systems.
In this way, we reduce the need for heating or air conditioning to condition the interior of the home and achieve the comfort its occupants expect.
Specifically, the Passivhaus seal is awarded to a home if it incorporates sufficient energy-efficiency strategies (good insulation, good orientation, airtight walls, summer solar protection, etc.) and achieves a minimum heating demand of less than 15 kWh/m2 per year.
Residential buildings with Passivhaus certification
What are they?
Therefore, based on the definition of what the Passivhaus seal is, we can say that Passivhaus-certified buildings are those that meet a maximum total heating demand of 15 kWh/m2 per year.
Compared to conventional buildings, Passivhaus-certified buildings reduce occupants’ heating and cooling needs by 75% through passive strategies for capturing and storing energy.
The small amount of supplementary energy they require can easily be covered by renewable energy, making them a construction with a very low energy cost for both the owner and the planet.
What are they like?
Passivhaus-certified buildings must meet certain consumption-related requirements, achieved through a passive architectural design whose efficiency allows the building to heat and cool through natural, sustainable systems.
Heat is captured from the sun and dissipated through air currents.
Once consumption is reduced—and with it, energy needs and the need to store sufficient heat—the remaining contribution is minimal and can be achieved with very little energy.
Aesthetically, Passivhaus-certified buildings do not have to be very different from conventional buildings. In other words, these buildings neither require nor imply the use of materials, products, or architectural styles different from those used in standard construction; instead, they rely on optimizing existing resources through passive techniques.
By passive techniques we mean: a good form factor that reduces the surface area in contact with the exterior to lower heating and cooling needs; correct window orientation to take advantage of the sun’s heat when they are closed and natural ventilation when they are opened; installing solar shading to prevent overheating in summer; insulation, etc.
In short, the design of Passivhaus-certified buildings is based on optimizing four aspects:
– Compactness
– Orientation
– Solar protection
– Solar reflectivity
Compactness
When we talk about compactness, we mean the relationship between the façade surface area and the volume.
Logically, if a building has a small façade surface area, it will be more compact and therefore easier to control in terms of heating and cooling.
In addition, we can state that the smaller the façade surface area, the lower the energy losses.
Orientation
Likewise, orientation is a second vital factor in the design of a passive building—especially if it aims to obtain Passivhaus certification—since good orientation makes it possible to harness solar energy and protect the home from atmospheric factors such as wind.
Protection and reflectivity
Finally, the third and fourth factors to consider are closely related: solar protection and solar reflectivity.
These are two factors that are likely considered most useful in summer, when it is most important to avoid solar radiation by using reflective materials or shading elements such as porches or overhangs.
In addition, for our building to achieve Passivhaus certification, it must meet the following 5 requirements:
1. Have excellent thermal insulation. Above all, ensuring that the envelope elements (external walls, roof, and slab…) have low thermal transmittance.
2. Always use high-performance windows and doors. The quality of the joinery must never be questioned in the design of Passivhaus-certified buildings. We must opt for joinery with low thermal transmittance and double- or triple-glazed windows, depending on the climate.
3. Avoid thermal bridges. That is, avoid potential points where the continuity of the insulation is imperfect. Passivhaus-certified buildings ensure maximum continuity of the external envelope, minimizing thermal bridges and preventing the formation of condensation and surface mould.
4. Use mechanical ventilation with heat recovery, to guarantee indoor air quality while ensuring airtightness at the same time.
To minimize the building’s energy demand, the Passivhaus standard establishes an air renewal rate of approximately 30% of the volume of interior spaces, although in summer it is usually somewhat higher.
5. Airtightness. In a Passivhaus construction, the envelope must be as airtight as possible, ensuring there are no draughts around windows and that the mechanical ventilation system is more efficient.
By ensuring the airtightness of a building’s indoor air, we can anticipate and prevent moisture problems, increase energy efficiency, improve acoustic insulation and indoor comfort—in short, create a healthy indoor environment.
Why? Advantages of Passivhaus-certified residential buildings
With small actions and by applying these concepts in the design phase, we can build residential buildings that use less energy for heating and therefore, in the long run, help us save in that respect, while also generating a smaller environmental footprint than if we build a conventional building that does not take these aspects into account.
Passivhaus-certified buildings are a sound construction investment because, if they achieve the certification, they will receive a highly positive rating and certification worldwide.
They also guarantee indoor comfort for occupants, while providing a completely healthy environment, free of damp, with a constant average annual temperature and 100% renewed air quality.
Passivhaus Database
There are numerous examples in Europe and around the world of Passivhaus-certified buildings.
Studying them can be interesting and a good exercise, and they can inspire us if we are considering building or carrying out a project of this kind.
For this purpose, there is the Passivhaus platform.
In addition to providing information on more theoretical topics related to how to achieve the certification, it includes an interactive search tool where we can find examples of single-family homes, renovations, residential buildings, facilities, etc.—all certified with the Passivhaus seal.
The search engine also includes filters that allow us to narrow down the results.
We can select the building’s location, its typology, the type of energy strategy used, as well as certain construction-related classifications.
Once the search is launched, the results appear as expandable cards with the most relevant data for each project and some images.
The information we obtain is very basic, but it can serve as a starting point for a more targeted search for a specific building or architecture team.
Passivhaus Interactive Map
There is also another similar search tool, linked to Google Maps.
When we access it, we immediately find an expandable world map with “pins” marking each location where there is a house, residential building, office building, or facility classified among low environmental impact, passive, efficient buildings—and, of course, also Passivhaus-certified buildings.
The colour of the pins distinguishes each type of building and provides a very visual way to filter the distribution of these buildings across Europe and worldwide.
Finally, if we click on a pin, a small information bubble opens with the year of construction, the typology or typological classification, a brief note and, in some cases, a link to the Passivhaus platform mentioned above to view more details about the building in question.
Having reviewed the landscape and benefits of Passivhaus-certified buildings, we only need to reiterate how strongly we at Slow Studio advocate for this type of construction and projects.
With our years of experience in passive, sustainable, efficient, and eco-friendly architecture, we can assure you that Passivhaus-certified buildings are a guarantee both in real-estate terms and on a personal level.