“Passive House” is the name of an international, climate-specific, construction standard that ensures healthy and comfortable indoor environments, while meeting stringent energy efficiency requirements in a cost-effective way.
The main principles of Passive building, regardless of which local standard you consider, are continuous insulation, air tightness, mitigation of thermal bridges, indoor air quality with heat recovery, and high performance windows and doors.
The Passive House Building Standard is internationally regarded as the most rigorous energy standard in the world, enabling over 90% reduction in heating and cooling demand compared to existing buildings, and over 75% compared to code compliant new constructions. As a result, the heating/cooling loads are generally reduced by a factor five, allowing for greatly simplified building services that also require a fraction of the maintenance. Similarly, the amount of renewable energy sources required for a Passive House building to achieve Net Zero is generally reduced by a factor three.
Aside from significant energy efficiency, the real benefit of the Passive House Building Standard lies in the considerably superior thermal comfort and healthy indoor air quality for the occupants. Building envelope components (e.g. windows) are selected on a climate-specific basis to provide suitable thermal protection, resulting in very evenly distributed temperatures. Thorough detailing avoids cold spots that would cause discomfort and that would be more exposed to the formation of mold and condensation. Indoor air quality is ensured via heat recovery ventilation, which supplies fresh filtered air and removes pollutants.
The Passive House Building Standard can be met in a cost-effective way via an integrated design approach combining conscientious architectural design, high quality building thermal envelope, and well executed construction. Resiliency in extreme weather events is ensured via a high building time constant, which is achieved by a combination of thermal insulation, avoidance of thermal bridges, and air tightness. This allows the internal environment to remain very steady if conditions suddenly change (i.e. if the power goes out during a blizzard).
Lower maintenance of building envelope components is an added bonus of Passive House buildings, as smart moisture management design factors in potential leaks, as well as the ability of assemblies to dry out again autonomously without active intervention. Passive House reliance on energy conservation through simpler technology (i.e. a well designed and built envelope) ensures a longer duration of the initial investment as compared to energy compensation via renewables. While the expected life span of a PV system does not exceed 25 years, field testing on decades old Passive House buildings has proven these can live 50+ years with just ordinary maintenance.
Frequently Asked Questions about Passive House:
What is the difference between “Passive House”, designing with “passive principles”, and the “passive solar” movement?
Read our Houzz article. It’s important that you do.
A house or building without a heating system? How is that possible?
A Passive House doesn’t necessarily need a traditional heating system. The building envelope allows for very little heat losses, so the remaining heating/cooling demand can be provided by mechanical ventilation.
Why is it better to invest in the building envelope, as opposed to the heating/cooling services of a house or building?
Today there is a lot of talk about renewables: photovoltaic, wind, geothermal. Everyone asks which one is the best value, the most ecological and economical? A Passive building is removed from this discussion because it requires so little energy that an expensive renewable energy system is not necessary. This means that the building is much simpler to use and has associated maintenance costs that are much lower. Our motto at Emu Systems is “conservation before compensation”.
Does a Passive House cost more than a traditional house?
It depends how you calculate the cost of a building and what kind of building you’re looking at. For single-family homes, yes, it is possible that total capital construction costs are slightly higher than conventional costs. But the hidden value of health, comfort, and durability are more difficult to quantify. Once you start calculating maintenance and utilities costs for the life of the house, a Passive House quickly becomes much less expensive. Larger buildings, such as multi-family or commercial spaces, can much more easily reach market-rate costs if integrated design approaches are used. In these cases, Passive building is even more cost-effective than conventional construction.
Besides houses, can other types of buildings be Passive?
Yes, there are many examples of Passive schools, libraries, churches, offices, etc.
What is the architectural style of a Passive House or Building?
Whatever you like! Building a house to the Passive standard does not mean that you have to adhere to one particular design aesthetic.
Can I renovate my existing building into a Passive House?
Yes! Many Passive buildings are, in fact, renovations or restructures.
How important is the orientation of a Passive House?
A Passive House heats itself with passive solar gains, so the orientation with respect to the sun can have a very big impact on the amount energy available. This does not mean, however, that it is impossible to construct a Passive House without the ideal orientation. It just means that other considerations need to be made in the calculations.
Are Passive Houses made of wood or masonry?
Both and neither. The standard does not prescribe a specific building material.
Why does a Passive House need mechanical ventilation?
Mechanical ventilation guarantees comfort and healthy indoor air quality by exchanging dirty or moist air (such as in the bathroom or kitchen) for freshly filtered air.
Can I still open the windows?
Of course! Just as in any normal house or building, the windows may be fully operable.
Why is it a good idea to complete the certification process?
(1) The certification process offers a certain set of guidelines for the contractor to follow to ensure quality of construction (2) Having the certification will increase the market value of your house or building.
How do you air condition the space in summer time? Is there direct/mechanical ventilation?
In Passive House buildings, you can use conventional heating/cooling/dehumidification services, as long as they are safe and that they are accurately sized for the actual heating/cooling loads of the building. Typically, H/C loads are 90% smaller than code-built buildings, because the thermal envelope is much more efficient. Typical H/C services include radiant surfaces (e.g. in-slab, ceiling etc.), as well as radiators, fan coils, or supply air.
In the multifamily space, how would you monitor ventilation through common areas such as hallways, club houses, etc.?
You design these spaces to be either supply air rooms, extract rooms, or transition-ventilation rooms, depending on size/use/scope.
Regarding medical space, are there any health codes and/or violations using these systems?
For any kind of building, you need to comply with local/national code besides the requirements of the Passive House Standard. A case study of a hospital built to the PH Standard can be downloaded here: https://www.passivehouse-international.org/upload/20180215_Pressemitteilung_Passivhaus_Klinik_Rohbau_EN.pdf
How do you manage BTUs? For example, if you have a group of 15 people in your home for holidays and other events, how would you manage the temperature? Typically, you see people turn the air down when the party is present (since BTU increased the temperature), then back up when the party leaves (since BTU is no longer a factor).
Just like in non-Passive House buildings, you have a thermostat controlling the temperature inside the building. Depending on the type of heating/cooling system you have (e.g. radiant vs supply air), you may have the option to regulate the internal temperature by whole building, by zone or by individual room. You could also link the heating/cooling to a timer or to an IR sensor to detect presence. This is not specific to PH buildings.
How do you control your temperatures for comfort levels? For example, people will turn temperature down if they are hot (working out, experiencing a fever, etc.) and up when they are cold (after playing outside in the winter, etc.).
A Passive House thermal envelope is very insulated from the outside, resulting in a very constant indoor environment. Of course, glazing has to be designed for passive solar gains, as well as to prevent overheating. A case study of a PH built in Dubai is available here: http://www.passivhausprojekte.de/index.php?lang=en#d_5065
In cold climates, it is nice to provide the option to have a wood burning stove (as in the case you mentioned, after playing outside in the snow). This is perfectly acceptable in a PH building (as long as the installation is airtight), and – contrary to popular belief – would not lead to overheating if properly designed. We installed one wood burning stove per PH we built in Northern Italy, and they have not yet turned them on because they never needed to.
In the multifamily space, how would you control temperatures per unit? Would this be completed through separate ventilation systems?
It depends on the project scope and on your overall strategy. You can provide heating/cooling via radiators/radiant surfaces and be done with it. If you are using the supply air as a vehicle for your heating/cooling (which would save you a lot of money), in a multifamily you can install individual coils per unit to allow better control. This would allow for better control (i.e. as opposed to having one centralized heating/cooling system for the entire building, which would be the cheapest), and would mitigate the fact that different units potentially have different orientation and therefore different passive solar gains.
What is the temperature range you have control over?
It depends on the type of heating/cooling system you choose. With supply air, temperatures tend to be very even throughout the unit. With other systems (radiators, radiant surfaces etc.) you have more control.
What is the typical cost increase (%’s) for passive vs. standard building?
It depends on the type and price range of buildings In single family buildings, you can expect the overall cost to be higher than code-built. The % will depend on other factors. If you have expensive finishes (granite countertops and imported floor tiles), your % premium for PH will be considerably lower than if you are looking at affordable housing.
In multifamily, if the architectural design is done properly (orientation, form factor, % and distribution of windows), it doesn’t necessarily cost more.
Items that will drive cost up compared to code: windows and ventilation.
How do you achieve such low R-Values ?
You insulate a lot. Unlike code, there are no mandatory R-values per assembly, as long as you avoid mold/condensation, and that your overall building meets the required efficiency. That means that you can insulate the floor and ceiling more, and the walls less, so that you don’t eat up too much of your floor area. Also, there are no preferred insulation types, as long as the declared R/in value is realistic for the climate you use it in. We want to make sure that the buildings will perform the way they are designed for.
In Multifamily spaces, where you don’t have different directions of sun exposure, how would you manage the heat from the sun? For example, if you enjoy natural lighting and don’t want to use high technology blinds to equalize temperatures in your home, how else could that be done in apartments?
You design glazing to provide the required passive solar gains (in winter) and to avoid overheating (in summer). This is done by choosing proper insulated glass unit (IGU) buildup, making sure that it works for the building overall and for the individual space. Depending on scope and size of the project, you can specify different characteristic of the IGUs by building orientation. We tend to avoid that because things can happen, and different glazings may end up in different orientations. Keep things simple, if possible.