Energy Efficient Fans, MVHR and The Passivhaus Standard
The Passivhaus standard is widely recognised in the construction industry and provides specific criteria to increase the energy efficiency of new and existing buildings in line with future sustainability and net zero goals. The overall design and construction of a building including the integration of effective and efficient HVAC systems must meet the full criteria for it to be Passivhaus certified.
While Passivhaus buildings are airtight, we’ll cover more on this later, they incorporate a controlled mechanical ventilation system with heat recovery. This ensures a constant supply of fresh air while recovering and reusing the heat from the outgoing air, further enhancing energy efficiency. The two air streams pass through separate channels in the heat recovery unit (known as the heat exchanger), and heat is transferred from one stream to the other without mixing the air itself.
By recovering and reusing the heat from the exhaust air, the heat recovery unit helps to significantly reduce the energy required to heat or cool the incoming fresh air. This contributes to the overall energy efficiency of the building, as the heating or cooling demand is reduced. In colder climates, this can be particularly effective in retaining indoor warmth.
The mechanical ventilation system is designed to maintain a balanced airflow, meaning that the amount of air being supplied into the building is roughly equal to the amount of air being exhausted. This helps avoid pressurisation issues and ensures that the indoor environment remains comfortable and well-ventilated.
Effectively designed heat recovery systems and the correct selection of integrated fans are important factors for ensuring good air quality, reducing heat losses and the overall energy consumption of a building. Learn more about EC forward curved fans for heat recovery systems here. Our Ecofit fans are integrated into the MVHR units produced by the UK’s leading MVHR manufacturers.
Mechanical ventilation with heat recovery systems installed in Passivhaus buildings aims to strike a balance between energy efficiency and indoor comfort.
Mechanical Ventilation with Heat Recovery (MVHR):
While Passivhaus buildings are airtight, we’ll cover more on this later, they incorporate a controlled mechanical ventilation system with heat recovery. This ensures a constant supply of fresh air while recovering and reusing the heat from the outgoing air, further enhancing energy efficiency. The two air streams pass through separate channels in the heat recovery unit (known as the heat exchanger), and heat is transferred from one stream to the other without mixing the air itself.
By recovering and reusing the heat from the exhaust air, the heat recovery unit helps to significantly reduce the energy required to heat or cool the incoming fresh air. This contributes to the overall energy efficiency of the building, as the heating or cooling demand is reduced. In colder climates, this can be particularly effective in retaining indoor warmth.
The mechanical ventilation system is designed to maintain a balanced airflow, meaning that the amount of air being supplied into the building is roughly equal to the amount of air being exhausted. This helps avoid pressurisation issues and ensures that the indoor environment remains comfortable and well-ventilated.
Effectively designed heat recovery systems and the correct selection of integrated fans are important factors for ensuring good air quality, reducing heat losses and the overall energy consumption of a building. Learn more about EC forward curved fans for heat recovery systems here. Our Ecofit fans are integrated into the MVHR units produced by the UK’s leading MVHR manufacturers.
Mechanical ventilation with heat recovery systems installed in Passivhaus buildings aims to strike a balance between energy efficiency and indoor comfort.
Other elements outside of mechanical ventilation covered by the Passivhaus standard include:
Air tightness of the building: Passivhaus buildings must be airtight with very small gaps with an air change rate less or equal to 0.6 air changes an hour at 50 Pascals pressure. Air tightness reduces the infiltration of outside air and prevents drafts. This helps to maintain a stable indoor climate and prevents energy loss. Thermal insulation: The envelope of the building must be very well insulated with U-values (thermal transmittance) ranging from 0.10 to 0.15 W/(m²K). Good thermal insulation reduces heat loss and prevents moisture build-up. Absence of thermal bridges: Thermal bridges should ideally be avoided to meet the criteria for thermal free Passivhaus design, however, where they can’t be completed avoided, they should be minimised below the set value of 0.01 W/(mK). Insulated Windows: Windows need to be well insulated to prevent heat transfer with a low U-value of 0.80 W/(m²K) or less and a solar transmittance value of around 50% which is the proportion of the solar energy available for the room. Renewable Primary Energy Demand: The ‘Passivhaus plus’ standard focuses on the renewable energy generation of Passivhaus buildings. It was designed to replace the original standard now known as ‘passivhaus classic’, which had no requirement for renewable energy generation and a max renewable primary energy (PER) of 60 kWh/m2/yr. The renewable primary energy standard uses only recycled energy to power electricity grids and was introduced by the Passivhaus institute. Reduced Carbon Emissions: According to the passivhaus institute, buildings are accountable for 35% of total global energy consumption. With the aim to meet future net zero targets, new and existing buildings are encouraged to adopt the passivhaus standard. Existing buildings may struggle to meet all the criteria due to the existing design structure of the building, therefore, the EnerPHit standard for retrofit projects can be adopted which entails a more relaxed criterion.Benefits of the Passivhaus Standard:
- Improved procedures in construction, enhancing quality
- Reduced energy consumption
- Lower emissions in line with net zero targets
- Improved performance
- Lower energy costs
- Comfortable and controlled ventilation
- Improves overall air quality
- Pollution protection
- Robust Structure for minimal risk of damages
- Low maintenance
- More economical
- Reduces external noise impact