Enerphit Passivhaus retrofit case study: Zetland Victorian townhouses in Manchester

Enerphit: the Passivhaus retrofit method

How to achieve the Passivhaus standard of energy efficiency in an older property

By Caroline Rodrigues | 27 October 2020

Enerphit is the Passivhaus certificate for achieving highly energy-efficient home retrofits. Just as with a new-build, insulation, airtightness and renewables all come into consideration. With the help of an Enerphit retrofit plan, the Passivhaus Institute‘s step-by-step approach happens in two or more stages. Architect Tom Raymont from Arboreal Architecture outlines what is involved.

Experience is key

Start your plans by finding a good architect. You want one with experience of a deep retrofit and preferably an accredited Passivhaus designer. They need expertise in understanding how heat, air and moisture move through a building.

Also, an independent assessor, working alongside the Passivhaus-trained architect, is necessary if you want to achieve a certified Enerphit retrofit. This is more expensive than a deep retrofit to high energy efficiency levels. It is possible to design all the improvements but only carry them out incrementally as funds become available.

zetland house manchester passivhaus renovation - grand designs

Ecospheric retrofitted this pair of Victorian townhouses to Enerphit Plus standards with recycled newspaper insulation, an MVHR system and PV panels, costing around £250,000 per house. Photo: Rick McCullagh

Layers of insulation

Adding new layers of insulation to the inside or outside of a building may change its appearance. This includes the details at windows, doors and other junctions.

Technically, moisture is the key issue and it’s very important that the condensation risk is designed out. Traditional insulation products are often the most reliable. Wood-fibre boards, cork boards and blown cellulose all have excellent performance. They are plant-based and are breathable.

V-shaped timber beams in an Enerphit Passivhaus retrofit living room

Inside one of the above Victorian townhouses, where hot water is stored in a tank using a thermocline control to maximise efficiency and the PV panels generate more power than they use. Photo: Rick McCullagh