Retrofit

You don’t have to live in a new build to reap the benefits from modern energy efficient principles.

At Stoic Homes, we approach retrofitting as an act of respect — for the building, for the environment, and for the people who live within. Using Passivhaus EnerPHit principles, natural materials, and modern detailing, we breathe new life into old homes — making them warmer, quieter, healthier, and radically more energy-efficient. Thoughtful, resilient, and built to last — just as they should have been from the start.

Key Elements of a Retrofit

Insulation

Solar + Batteries

Ventilation

Air Tight Measures

Heat Pump

Past Retrofit Projects

  • Penwortham Retrofit

    Whole house retrofit of a detached 4 bedroom house estimated to have been built in the 1920s

    Problems:

    • Poor air quality in kitchen and bedroom
    • High annual heating costs
    • High annual electricity cost due to ownership of 2x electric vehicles
    • Unstable internal temperature throughout house
    • Damp & condensation issues
    • Excessive heat-loss via windows & doors
    • Poor air tightness (17ach/h @ 50pa)

    Solutions:

    • Internal Wall Insulation (Rigid Wood Fibre)
    • Ground Floor Insulation (Rigid Wood Fibre)
    • Upgraded Windows & Doors (triple glazed timber frame PH certified)
    • MVHR (Zehnder®)
    • Solar PV + Battery Storage (8.2kWp + 15kWh)
    • Air Source Heat Pump (8KW, Midea)
    • General Repairs
    • Air tightness upgrades
    • Mains water filtration, ionisation

  • Soundskills Community Centre Retrofit

    Whole house retrofit of a mid-terrace community centre estimated to have been built in the 1970s

    Problems:

    • Poor air quality throughout
    • High annual heating costs
    • Unstable internal temperature throughout building
    • Roof was leaking through the valley
    • Excessive heat-loss and drafts via windows & doors
    • Poor air tightness (15.5ach/h @ 50pa)

    Solutions:

    • New reclaimed welsh slate roof
    • Cellulose loft insulation and boarding
    • Upgraded Windows & Doors (triple glazed aliminuim)
    • MVHR (Zehnder®)
    • Solar PV + Battery Storage (4.2kWp + 5kWh)
    • Air Source Heat Pump (12KW, Midea)
    • Electric loft ladder
    • Air tightness upgrades
    • Full redecoration throughout

  • Blackpool Retrofit

    Whole house retrofit of a detached 3 bedroom house estimated to have been built in the 1920s

    Problems:

    • Poor air quality in kitchen and bedroom
    • High annual heating costs
    • Old kitchen was unusable
    • Unstable internal temperature throughout house
    • Damp & condensation issues
    • Excessive heat-loss via roof
    • Poor air tightness due to open fire places

    Solutions:

    • Cellulose loft insulation and boarding
    • Ground Floor Insulation (Sheep’s wool)
    • Upgraded Windows & Doors (triple glazed to north facing side)
    • Insulated chimney breast
    • Full new kitchen and tiling
    • New gas boiler in new location
    • General Repairs
    • Air tightness upgrades

  • Fulwood Retrofit

    Part retrofit, and full renovation of a detached house estimated to have been built in the 1990s

    Problems:

    • Conservatory was unusable due to unstable temperatures
    • High annual heating costs
    • Kitchen was very small and aged
    • Living room was dark and aged
    • Excessive heat-loss and drafts via windows & doors

    Solutions:

    • Converted living roof into the new kitchen
    • Installed new window opening to bring more light into the kitchen
    • Conservatory roof was insulation and boarded on the internal side
    • Bioethanol two-way fire installed into new chimney breast
    • New oak internal doors throughout
    • Custom book case
    • Converted conservatory into new living room
    • Full redecoration throughout

  • Mellor Brook Retrofit

    Whole house retrofit of an end-terrace house estimated to have been built in the 1920s

    Problems:

    • Very drafty throughout house
    • High annual heating costs
    • Kitchen was dated and didn’t fit the owner’s needs
    • Roof was leaking through the valley
    • Excessive heat-loss and drafts via windows & doors
    • Poor air tightness

    Solutions:

    • Installed kitchen including tiling and granite worktops
    • Upgraded internal vestibule door and top light
    • Upgraded Windows & Doors (black with period features)
    • Air tightness upgrades
    • Full redecoration throughout

FAQ’s

  • A high performance retrofit project utilising natural materials (where possible) typically costs between £900-1500 per meter squared. So for an average 3 bedroom home of 100m2, this would be between £90-150k depending on how complicated the design & scope of works is.

  • For a full house deep retrofit of a typical 3-bed detached house, it normally takes 2-3 months for everything.

  • 1.      A high-performance retrofit upgrades an existing building to dramatically improve its energy efficiency, comfort, and indoor air quality. It typically involves the following:

    a.       insulating the building fabric,

    b.      improving airtightness,

    c.      upgrading windows,

    d.      installing efficient ventilation and heating systems.

    The goal is to reduce energy demand, carbon emissions, and running costs—often to near new-build standards. Upgrades are measurable, and there are two main building standards to aim for, these are Enerphit and AECB Carbonlite.

  • a.      Both AECB and Enerphit revolve around the same fundementals….. but with differing levels of performance, as outlined below:

    Metric

    EnerPHit Requirements

    Space Heating Demand

    ≤ 25 kWh/m²/yr (alternatively: peak heat load ≤ 10 W/m²)

    Primary Energy Demand (PER)

    ≤ 120 kWh/m²/yr (for all uses: heating, hot water, appliances, lighting)

    Airtightness

    ≤ 1.0 air changes/hour @ 50 Pa (n50)

    Thermal Bridge Free Design

    Required – All thermal bridges must be minimized and assessed

    Ventilation

    Mechanical ventilation with heat recovery (MVHR) required; ≥ 75% heat recovery

    U-values (Components)

    Windows: typically ≤ 0.85 W/m²K; Opaque elements: ~0.15–0.25 W/m²K

    Moisture Control

    Must ensure no risk of condensation or mould (e.g., surface temps ≥ 17°C)

    Certification Options

    EnerPHit Standard or EnerPHit Component Method (if some existing elements are retained)

    Metric

    AECB CLR Requirements

    Space Heating Demand

    ~40 kWh/m²/yr (may vary depending on location and strategy)

    Primary Energy Demand

    ≤ 120 kWh/m²/yr (aligned with EnerPHit, but can vary slightly)

    Airtightness

    ≤ 1.0–2.0 air changes/hour @ 50 Pa (depending on tier of CLR)

    Thermal Bridge Free Design

    Encouraged but not always required

    Ventilation

    MVHR strongly encouraged but not strictly mandatory

    U-values (Components)

    Typically: Windows ≤ 1.2 W/m²K; Walls ≤ 0.2–0.3 W/m²K

    Moisture Control

    Condensation and moisture risks must be managed

    Certification Options

    CLR performance tiers (e.g., CLR Silver, Gold) offer flexibility

     

  • Yes, this is the perfect time to retrofit your home. Complement the decorative, aesthetic, or functional alterations you wish to make whilst improving the energy efficiency of your home.

  • Yes. Research conducted by the RIBA showed that for every EPC your home improves by, the sale price of the home increases by approximately 2%.

  • Yes, you can finance a retrofit through various options, including government grants, low-interest green loans, or energy-efficient mortgage top-ups. Contact us if you want help exploring your options.

  • Natural materials such as wood fibre insulation, lime plaster, hemp, and cork are highly compatible with high-performance goals. They offer good thermal performance, excellent moisture regulation, low embodied carbon, and are particularly well-suited for breathable and traditional buildings.