This post is part of our series that shares questions we regularly receive about Passivhaus and low energy construction. We will be posting a new one every week. Explore our Blog to learn all about why designing buildings to low energy standards like Passivhaus delivers a lot more than just energy savings.
As sustainability becomes increasingly paramount in home construction, terms like "energy-efficient homes" and "Passivhaus" often pop up. While both prioritise energy efficiency, they aren't quite the same. Let's uncover the nuances between these two construction methodologies.
Defining energy efficient homes:
An energy-efficient home, in its broadest sense, is designed to reduce energy consumption, thereby minimising greenhouse gas emissions and utility bills. These homes incorporate various techniques and technologies to achieve this:
Insulation: Proper insulation in walls, roofs, and floors reduces heat transfer, maintaining a comfortable indoor temperature.
Efficient Appliances: 'A-rated' appliances consume less energy while providing the same functionality as their conventional counterparts.
Advanced Windows: Double or triple-glazed windows, sometimes filled with inert gases, minimise heat loss.
Renewable Energy: Many energy-efficient homes use solar panels, wind turbines, or other renewable sources to generate electricity.
The specifics can vary widely, depending on local regulations and climate. However, the unifying factor is a reduction in energy use compared to conventional homes.
Unpacking the Passivhaus Standard:
Passivhaus, originating from Germany, represents a stringent, holistic approach to energy-efficient construction. It's not just about incorporating a few energy-saving techniques but rather a comprehensive method that ensures minimal energy usage. Key features include:
Ultra-insulation: Passivhaus buildings typically have much thicker insulation than even most energy-efficient homes.
Airtightness: One of the hallmarks of the Passivhaus standard is its airtight construction, preventing unwanted drafts and energy loss.
Thermal Bridge-Free Design: All junctions and connections in the building are designed to prevent heat transfer.
Mechanical Ventilation with Heat Recovery (MVHR): This system ensures fresh air intake while retaining most of the internal temperature by transferring heat from the outgoing stale air to the incoming fresh air.
Passive Solar Gain: By strategically placing windows and using advanced glazing, a Passivhaus utilises the sun's energy to aid in heating the home.
For a building to be termed a Passivhaus, it must meet specific criteria set by the Passive House Institute or similar accrediting bodies.
The differences:
Rigidity vs. Flexibility: Passivhaus has a rigid set of criteria that must be met for certification. In contrast, an energy-efficient home can be a blend of various techniques and technologies that might not adhere to a specific standard.
Performance Assurance: With its stringent criteria, a Passivhaus guarantees a certain level of energy performance. An energy-efficient home might not have such guaranteed performance metrics.
Construction Techniques: The construction techniques in a Passivhaus are specific, ensuring airtightness, absence of thermal bridges, and optimal passive solar gain. An energy-efficient home might not employ all these methods, although it will use some.
Conclusion:
While both new build energy-efficient homes and Passivhaus constructions aim to reduce energy consumption, the Passivhaus standard takes a more rigorous, all-encompassing approach. Energy-efficient homes incorporate methods and technologies to save energy, but without the strict criteria and guaranteed performance of a Passivhaus. For those seeking the pinnacle of energy-efficient construction, the Passivhaus standard is the gold standard. However, any step towards more energy-efficient living is a step in the right direction.