Passive House vs. Active House


In light of the news of the completion of the active house in Thorold, I've been asked a few times now: What the heck is an active house?

I'll give you a quick an dirty comparison, but keep in mind, I'm a passive house designer, and I can only guarantee that all my Passive House knowledge is 100% accurate.

Broadly speaking, Passive House looks at what the ideal indoor climate conditions for a human are and then builds a most cost efficient house that accommodates those criteria. You end up with a house that is very comfortable and healthy to live in. (On a side note, this is exactly the opposite way that a regular house is built, which starts with someone dreaming up a building shape and then they figure out how they can make it inhabitable). The term passive in Passive House refers to how the house is being heated; in moderate climate (Vancouver area, Central Europe) one ends up not needing any active heating, the off-heat from people, pets, appliances, lighting, etc, is enough to keep the house warm. (On a second side note, this does not mean that you end up with a bunker with no windows.)

An Active House also focusses on the comfort of the inhabitant and energy preservation (it also uses a few other criteria, but lets focus on those two for now). The word active refers to the active controls of the house, automation is key for ventilation and keeping the house from overheating or undercooling. (third side note, Passive Houses uses active technology as well, mechanical ventilation and automated blinds are not uncommon)

In essence that is the big difference. I've seen very heated discussions between active and passive house fans, and both sides have very good arguments. Here are the main arguments for each type:

  • Passive House: if you are already building a house, you might as well build it right and drastically reduce energy consumption, ideally down to 15kWh/m2a and below (the threshold for passive house).
  • Active House: what do we do with the existing building stock? It can be very costly to reduce energy consumption to Passive House levels, are there other methods to reduce energy costs and still have a high level of comfort?

If you listen to this discussion in Europe, both sides are just very fine nuances of each other. They have a lot of experience with Passive House and are now trying to tweak things. The danger that I see here in North America, is that before we even try to minimize the energy consumption by optimizing the building envelope, we start by tossing the principles of the Passive House out the window - which mainly focus on plain old physics of heat transfer - and step right to automation technology. This will indeed help some, but we need to first focus our attention to building better buildings.

For Canada and North America, the strategy should be to first implement the knowledge of Passive Houses and then go and ad automation and tweak the economics, always keeping longevity and healthy environments of our buildings in mind.

Use this as an introduction to this topic for now. This topic can be taken to the n-th degree, and will certainly kick lose some heated arguments. Let the games begin!