Thermal Envelope

An enhanced thermal envelope is crucial in the EnerPHit standard for retrofitting existing buildings to achieve high energy efficiency and comfort. The focus is on improving the thermal performance of the envelope by adding high-quality insulation to walls, roofs, and floors, where feasible, to minimize heat loss. Airtight construction techniques, such as sealing gaps and cracks, and upgrading windows and doors to high-performance units with low U-values, further enhance the thermal performance. 

Optimising Thermal Envelope

Although EnerPHit allows for slightly higher U-values compared to the Passivhaus standard for new builds, the goal remains to significantly improve overall thermal performance. By optimizing the thermal envelope, EnerPHit retrofits create a more stable and comfortable indoor environment while minimizing energy required for heating and cooling, leading to reduced energy consumption, lower utility bills, and enhanced living experience for occupants.

Triple Glazing

When retrofitting buildings to meet EnerPHit standards, upgrading windows is crucial for improving energy efficiency and comfort. While Passivhaus typically requires triple glazing, EnerPHit allows for more flexibility due to existing structural constraints. Installing double glazing with low U-values and airtight seals can often suffice, minimizing heat transfer, reducing draughts, and maintaining stable temperatures. In some cases, triple glazing may be feasible and desirable for superior insulation and acoustic performance, especially in colder climates or when maximum efficiency is desired. 

Reduce Heat Loss

Regardless of glazing choice, proper installation is key to ensure sealing and integration with the enhanced thermal envelope. By improving window performance, EnerPHit retrofits significantly reduce heat loss, lower energy consumption, and create a more comfortable living environment.

Airtightness

Airtightness is crucial in the EnerPHit standard for retrofitting existing buildings to achieve high energy efficiency and indoor comfort. Improving airtightness involves identifying and sealing air leaks in the building envelope, including gaps around windows, doors, and penetrations, using appropriate sealing materials and techniques. While EnerPHit allows for slightly higher air leakage rates compared to Passivhaus for new builds, the goal remains to significantly reduce air leakage.

Maintains Consistent Air Quality

Controlling air infiltration enhances the effectiveness of ventilation systems, maintains consistent air quality, and reduces energy required for heating and cooling. This leads to lower energy consumption, reduced utility bills, and a more comfortable living environment. Improved airtightness also helps prevent moisture-related issues by minimizing uncontrolled moisture transfer through the building envelope.

MVHR

Mechanical Ventilation with Heat Recovery (MVHR) is essential when retrofitting buildings to meet the EnerPHit standard, improving energy efficiency and indoor air quality. In an EnerPHit retrofit, an MVHR system extracts stale air and supplies fresh, filtered outdoor air, transferring heat from the outgoing to the incoming air to minimize heat loss and reduce energy required for heating. 

Improves Indoor Comfort

Although MVHR efficiency may be slightly lower in EnerPHit retrofits compared to Passivhaus new builds due to ductwork constraints, they still maintain consistent fresh air supply and stable temperatures. MVHR systems work with the improved airtightness of the building envelope, ensuring controlled ventilation and preventing moisture issues. By reducing reliance on additional heating and maintaining excellent air quality, MVHR systems in EnerPHit retrofits lower energy consumption, improve comfort, and create a healthier living environment.

ASHP

When retrofitting buildings to meet the EnerPHit standard, an Air Source Heat Pump (ASHP) can enhance energy efficiency, although it is not a mandatory requirement. In an EnerPHit retrofit, an ASHP extracts heat from the outside air and transfers it inside to warm the building during colder months, and can reverse operation to provide cooling in summer. 

Significant Reduction to Utility Bills

ASHPs offer an environmentally friendly alternative to traditional fossil fuel-based heating systems by utilizing renewable energy from the air. However, the effectiveness of an ASHP in an EnerPHit retrofit depends on the building's improved thermal envelope and airtightness. When coupled with a well-insulated and airtight building envelope, ASHPs can significantly reduce energy consumption and utility bills while providing a consistent and comfortable indoor environment year-round.

Overheating

Managing overheating is crucial when retrofitting buildings to meet the EnerPHit standard, ensuring energy efficiency and comfort. In an EnerPHit retrofit, preventing excessive heat gain during warmer months can be challenging due to the existing building's orientation and design. Strategies include installing external shading devices, applying solar control films or high-performance glass, and improving the building envelope's insulation and airtightness to maintain a stable indoor temperature. 

Night Purge

Additional measures like night purge ventilation or strategic use of thermal mass can further assist in managing overheating. By implementing these strategies, EnerPHit retrofits effectively prevent overheating and ensure a comfortable living space during warmer periods.

Thermal Bridges

Eliminating thermal bridges is crucial when retrofitting buildings to meet the EnerPHit standard, improving energy efficiency and comfort. In an EnerPHit retrofit, identifying and addressing thermal bridges can be challenging due to the existing building structure. Strategies include adding insulation to specific areas, using thermal break materials, or applying specialized tapes and sealants to ensure insulation continuity. 

Prevent Condensation

In some cases, removing and replacing certain building elements may be necessary to achieve the desired thermal performance. While completely eliminating thermal bridges in an EnerPHit retrofit may not always be possible due to existing constraints, the goal is to minimize their impact. By reducing thermal bridges, EnerPHit retrofits help maintain stable indoor temperatures, reduce energy consumption, and prevent issues like condensation and mold, resulting in a more comfortable and energy-efficient living environment.