What is a Passivhaus?
Passivhaus is a building standard that focuses on reducing a structure’s energy use for heating and cooling by up to 90% compared to conventional buildings. You achieve this through thick insulation, airtight construction, high-performance windows, and mechanical ventilation with heat recovery. These features minimize heat loss and optimize solar gains, creating a stable indoor temperature with less reliance on active heating or cooling systems.
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FREE QUOTE REQUESTWhat is the Background of the Passivhaus?
The Passivhaus concept emerged in the late 1980s through a collaboration between Dr. Wolfgang Feist in Germany and Prof. Bo Adamson in Sweden. Their research focused on reducing energy consumption and improving indoor comfort. By the early 1990s, the first Passivhaus buildings were completed in Germany, demonstrating that careful design and construction could lower heating needs drastically. Today, Passivhaus principles are applied worldwide to create homes and buildings with reduced environmental impact.
What are the Principles of the Passivhaus?
The principles of the Passivhaus are including High Insulation, Airtight Construction, Thermal Bridge-Free Design, High-Performance Windows, Mechanical Ventilation with Heat Recovery (MVHR). Let’s learn it in detail.
High Insulation:
Purpose: Reduce heat transfer through walls, roofs, and floors.
Recommended Values: U-values (which measure heat loss) of approximately 0.10–0.15 W/m²K for walls, floors, and roofs in many climates.
Scientific Fact: Lower U-values indicate less heat loss, helping you maintain stable indoor temperatures without heavy heating or cooling systems.
Airtight Construction
Purpose: Prevent unwanted drafts and energy losses.
Standard: Air leakage should not exceed 0.6 air changes per hour (ACH) at 50 Pascals.
Reasoning: When you seal gaps and cracks, you keep heated or cooled air inside, cutting down on energy waste.
Thermal Bridge-Free Design
Purpose: Avoid parts of the building envelope that conduct heat quickly, like gaps around window frames or structural connections.
Standard: Linear thermal bridges should be minimized or eliminated (ideally ≤ 0.01 W/mK).
Scientific Fact: Thermal bridging accelerates heat loss, so reducing it improves overall insulation performance.
High-Performance Windows
Purpose: Enhance insulation and use sunlight for passive heating.
Typical Features: Triple glazing with U-values around 0.80 W/m²K or lower, plus low-e coatings and insulated frames.
Reasoning: Efficient windows allow solar gains on cold days and reduce heat infiltration on hot days, stabilizing indoor temperatures.
Mechanical Ventilation with Heat Recovery (MVHR)
Purpose: Provide fresh air, remove stale air, and recover heat or coolness.
Heat Recovery Efficiency: Often 75–95% in well-designed systems.
Scientific Fact: By transferring thermal energy from outgoing stale air to incoming fresh air, you reduce the need for extra heating or cooling, improving indoor air quality without wasting energy.
Passivhaus Standard
The Passivhaus standard is a rigorous, performance-based building standard for energy efficiency. It aims to create buildings that require minimal energy for heating and cooling while providing excellent indoor comfort. The Passivhaus standard is based on five key principles, which translate into specific performance criteria.
Space Heating Demand:
The annual space heating demand must not exceed 15 kWh/(m²a) (kilowatt-hours per square meter per year). In some climates, a peak heat load of 10 W/m² is also considered.
Reasoning: This low heating demand is achieved through high levels of insulation, airtightness, and heat recovery ventilation, minimizing heat loss during colder months.
Space Cooling Demand (in warmer climates):
The annual space cooling demand must not exceed 15 kWh/(m²a), or the peak cooling load should not exceed 10 W/m². This is achieved through shading, high-performance windows, and potentially night ventilation.
Primary Energy Demand:
The total primary energy demand for all domestic energy uses (heating, cooling, hot water, ventilation, lighting, and appliances) must not exceed 120 kWh/(m²a). This metric accounts for the energy used to produce and deliver energy to the building.
Reasoning: This criterion encourages the use of highly efficient appliances and renewable energy sources.
Airtightness:
The building must have an air change rate of no more than 0.6 air changes per hour (ACH) at 50 Pascals of pressure difference (n50 ≤ 0.6 h⁻¹). This is measured using a blower door test.
Reasoning: Minimizing air leakage reduces uncontrolled heat loss/gain and prevents drafts, improving comfort and energy efficiency.
Thermal Comfort:
The building must maintain a comfortable indoor temperature throughout the year. The operative temperature should be between 20°C and 25°C for at least 90% of the occupied hours.
Reasoning: This ensures a healthy and comfortable indoor environment, preventing overheating in summer and excessive cooling in winter.
Why are the Benefits of the Passivhaus?
The Benefits of the Passivhaus include Thermal comfort, indoor air quality, reduced energy bills, a Quiet and Peaceful Environment, and Increased Durability and Building Longevity.
Exceptional Thermal Comfort: Passivhaus buildings maintain a remarkably stable indoor temperature year-round. This is achieved through superinsulation, airtightness, and high-performance windows, which minimize heat loss in winter and heat gain in summer.
Superior Indoor Air Quality: Mechanical Ventilation with Heat Recovery (MVHR) systems continuously supply fresh, filtered air while extracting stale air. This results in improved indoor air quality, reducing allergens, pollutants, and CO2 levels.
Significantly Reduced Energy Bills: Passivhaus buildings require minimal energy for heating and cooling due to their high energy efficiency. This translates to significantly lower energy bills compared to conventional buildings.
Reduced Environmental Impact: By minimizing energy consumption, Passivhaus buildings contribute to reducing greenhouse gas emissions and combating climate change.
Quiet and Peaceful Environment: The high levels of insulation and airtightness also provide excellent sound insulation, creating a quieter and more peaceful indoor environment.
Increased Durability and Building Longevity: The focus on high-quality construction, moisture control, and prevention of condensation and mold growth contributes to increased building durability and longevity.
Can You Retrofit Passivhaus Standards to an Existing Building?
Yes, you can retrofit Passivhaus standards to an existing building, although it is more challenging than applying these principles to new construction. The process involves upgrading insulation, windows, and ventilation systems while addressing airtightness and eliminating thermal bridges.
Key Steps in Passivhaus Retrofitting
Improving Insulation: Add high-performance insulation to walls, roofs, and floors.
Installing High-Performance Windows: Replace old windows with triple-glazed units.
Improving Airtightness: Seal gaps, cracks, and joints in the building envelope.
Upgrading Ventilation Systems: Install a Mechanical Ventilation with Heat Recovery (MVHR) system.
Addressing Thermal Bridges: Fix structural elements that conduct heat, such as poorly insulated window frames or wall junctions.
What are the Challenges Retrofitting to Passivhaus Standards?
Space Constraints: Adding insulation or airtight layers may reduce interior space.
Structural Compatibility: Older buildings might require significant adjustments to meet airtightness goals.
Cost: Retrofitting can be expensive, with costs ranging from €600–€1,200/m² depending on the building’s condition.
