Passive House Retrofits: The EnerPHit Program
Last Updated: Feb 23, 2025One of the most common sayings in the green and sustainable housing industry is: "the greenest house is the one that is already standing." That idea was first expressed by Carl Elefante, a past president of the American Institute of Architects. Elefante based his reasoning on careful analysis of the embodied energy tied up in the construction materials that go into building a new home. Sustainable construction standards and technologies have certainly improved in recent years to the point that new homes can be much more energy-efficient than older homes. But, the total energy needed to source the building materials, manufacture, transport to the building site, and use them to build a new home has a considerably higher carbon footprint than the expected operational energy savings.
When deciding between tearing down and renovating, the numbers show that renovating older homes is undoubtedly more sustainable.
Table of Contents
- Historical Sustainable Renovation Challenges
- What is the EnerPHit Passive House Retrofit?
- Costs and Benefits of Passive House Renovations
- How Much Does an EnerPHit Passive House Retrofit Cost?
- How To Get Started With Passive House's EnerPHit Certification
- Bottom Line
Historical Sustainable Renovation Challenges
In the past, the scope of green renovation projects was somewhat limited. To be sure, you could always purchase a weatherizing kit to stop the drafts from around your windows and doors. But, the building envelope of many older homes was often seen as too compromised to make meaningful gains in terms of energy efficiency. In terms of thermal bridging, some older homes have frames that don't allow for maximum airtightness. If foundation issues are present, thermal bridging at the wall-to-floor junction can also be challenging. If your older home has very small rooms, thickening the walls to increase the insulation might not be feasible. New builds were seen as necessary if you were to achieve high thermal comfort levels with a radically reduced energy consumption.
What is the EnerPHit Passive House Retrofit?
The Passive House Institute (PSI) of Germany recognizes that many older buildings cannot achieve the passive house standard's rigorous demands for new homes. Luckily, the PHI's EnerPHit renovation certification allows renovations of older homes to the exacting passive house standards. The EnerPHit renovation plan, when implemented in its totality, can enable even the oldest and draftiest of homes to achieve energy efficiency and reduce energy demand. Certified homes generally reach reductions between 75 and 90%, and some have even achieved up to 93 percent.
How To Get Started With Passive House's EnerPHit Certification
Many homeowners don't have the financial resources to invest in a complete passive house retrofit and receive the EnerPHit certification. It is essential to keep in mind that there are still ways to make considerable improvements in your existing home's thermal performance and energy efficiency.
A simple energy audit will most likely help you identify the most important renovations that your home needs to increase its performance. In some cases, improving cavity wall insulation in a drafty bedroom might be enough to reduce your energy bills significantly. In other homes, replacing your old, single-pane windows with triple-glazed windows will do the trick.
Changing to a more energy-efficient home that seeks to achieve passive house standards can be a lifelong task. When your old boiler, furnace, or water heater finally dies, consider opting for a heat pump or solar water heating system to reduce your home's energy demand. Suppose your local government or utility offers rebates and incentives for home PV systems. In that case, you might find that it makes economic sense to transition to renewable energy.
Tobias Roberts
Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.
