By now, you certainly know that we like the Passive House concept and our goal of getting our house certified. But did you know that there are different certification classes under the Passive House Institute's certification body?
These different classes allow for different concepts to be applied depending on your project. When we first started specifying the requirements for our house, we weren't very familiar with these either, all we knew was that we wanted a certified Passive House.
Overview of Passive House Certifications
In the certification scheme, Passive House Institute offers three different certifications:
PHI Low Energy Building
Passive House is the well known and established standard, used mostly for new construction buildings.
EnerPHit uses the same Passive House basics, but applies them against renovations or retrofits of existing buildings. Because of the use of pre-existing sections of a building, like the foundation or basement walls, that were not designed and built to be very efficient, the requirements for EnerPHit are somewhat relaxed compared to Passive House requirements. This is to allow a practical and cost effective application of the Passive House principles in circumstances where the new construction requirements cannot be met.
For reasons where the above two certifications cannot be met, the institute has established a third certification called PHI Low Energy Building. There could be any reason really, but the most common ones are small buildings in cold climates, too much shade in the particular location, no building component availability or design and implementation problems.
So depending on your site or other circumstance, there is a certification for you!
Passive House and EnerPHit Certification Classes
Since Passive Houses use very little energy for heating and cooling compared to a regular house, many homeowners combine their Passive House with renewable energy sources, in particular solar panels and wind power. On top of that, clever building technology developments have led to even more efficient buildings over time. This only makes sense and the underlying trends resulted in the introduction of Passive House certification classes in 2015.
On the certification seals for Passive House and EnerPHit above, you can see the additions of the words "classic”, “plus” and “premium".
Classic certification means that the building does not have any renewable energy generation and is therefore certified against the standard requirements.
Plus class certification means that there is a slight excess of renewable energy being generated on site compared to the primary energy demand. This is essentially a Net Zero Energy building.
In the Premium class, the building generates significantly more renewable energy than is needed to operate the building. The excess can be stored or sold back to the grid.
As you can see from the info graphic below, from one class to the next the houses become more efficient by less energy demand and higher renewable energy production.
For classic certification requirements, the primary energy demand of a building for heating and cooling is used only. With the introduction of the certification classes, Passive House Institute introduced the Renewable Primary Energy demand (PER) that includes the energy required for heating, cooling, dehumidification, domestic hot water, lighting, auxiliary electricity and electrical appliances. Moreover, it considers the energy losses that come with storing renewable energy.
Why should this be considered?
The generation and supply of renewable energy varies depending on weather conditions. To have some of the generated energy available for use at times when demand is high but supply is low, the generated energy must be stored for some time. This energy storage process results in losses of energy. The PER demand calculation shows how much renewable energy has to be generated originally to cover the entire energy demand of a building. It also accounts for the storage losses.
Simply put, the solar panels produce electricity throughout the day when the sun is shining, but you would want this electricity stored until it’s time for your hot shower or watching TV after coming home from work.
With the addition of the certification classes, the Passive House concept can be taken to the next level by integrating renewable energy.
Which Passive House certification is right for you?
Passive House is a holistic concept with specific design features and building components that need to be picked out and ordered in time for their need on the construction site. It is therefore important to think about the certification level and your own requirements early on.
For us, it has been unclear whether we can integrate renewable energy at a reasonable cost into our new home build, or if the local regulations allowed certain applications. So our choice was easy to say we aim for a Passive House under the classic certification class.
Apart from knowing what's possible and what's not, there are two perspectives to approach the certification level choice:
Aim as high as possible, because if the certification criteria cannot be met 100%, you could fall back to a lower certification level; or
Pick the particular certification you want and allow the building engineers and designers the flexibility to plan the building to the exact target requirements.
Well, here we are. As with many things in life, there are many choices available, so which one will you pick?
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NOTE: All info graphics used above are credit to and copyrighted by Passive House Institute.