In our past anecdotes about Passive Houses, we have emphasised the importance of implementing the concept as a process and not just ticking boxes to meet a standard. It is the process of Passive House which distinguishes it as a building methodology. While other systems set up goals and parameters as a guide to eco friendly design, the way Passive Houses are designed not only ensure they reached their targets but is also an inbuilt guarantee of the building’s post construction performance of providing comfortable and healthy indoor spaces, and low energy consumption. 

This insurance of quality and performance of Passive House buildings results from intensive documentation and planning throughout the different phases from the initial concept design stage to execution. Independent on-site testing and reviews conducted post construction is integrated into the process as a given not an add-on. The end result of this process is a building which qualifies as Passive House standard. And while we are talking about results and standards, there are now more than one Passive House standard which can be achieved as we noted in our previous post. In addition to the original or Passive House Classic, there are four other levels of standard representing different applications.

The new classes apart from the original Passive House standard were created to onboard the transitioning of our energy supply structure from fossil sources to renewables. The challenge of meeting all our energy demands with renewables can only really be sustainable in the building sector if the focus is on reducing our energy usage to begin with. In parts of our world where heating requirements are high, a reliance on renewable energy may culminate in a ‘net zero’ building but still has a long way to go to achieve the energy demands of a European winter. In warmer climes the energy demand becomes more about cooling. But on hot days, photovoltaic systems can harvest solar energy to fuel electric heat pumps for cooling as well, so the targets are much more attainable. Either way, the energy efficiency of Passive House design accommodates for the ‘gap’ and complements renewables.

The Passive House Institute developed the different certification levels to better reflect the times and the growing need to integrate renewable energy into our buildings. So while the Classic level is certainly all about energy efficiency supported by performance testing and data, the Plus standard seeks to reduce the use of primary (or unsustainable) energy with additional energy generated by renewables. Passive House Premium pushes those parameters further, requiring more generation of renewable energy and relying increasingly less on primary fuels. EnerPHit is the retrofit standard which facilitates certification for buildings already built, although not attaining the efficiency performance of new buildings. There is also a further form of certification called the Low Energy Building which acknowledges buildings that are closely aligned but not quite compliant with all the criteria of a Passive House standard.

Of course, all these targets are a little hollow if the air in a building is unhealthy or uncomfortable to breathe. Stage right, MVHR systems. We need adequate ventilation to prevent harmful contaminants accumulating and mould from excess moisture from polluting the air we breathe in indoor environments. Passive Houses employ mechanical ventilation like vents and opening windows in combination with heat recovery or an MVHR system to ensure the quality of the indoor air is comfortable and efficiently achieved. The MVHR system pre-heats or pre-cools fresh air coming into a building according to the seasonal requirements. It uses a heat exchanger that operates on very little power to attain net energy reductions. The Passive House Institute certifies these systems, subject to rigorous testing, to meet minimum performance targets, and includes limiting noise levels.

Well, I think we’ve given you enough to chew on! Check in on us again to find out more about the ongoing Passive House revolution.