______ Project Overview

Located in Strachur on the east short of Loch Fyne, this social housing development consists of the formation of 16 social housing units by altering, combining and extending existing dwellings that are designed for over 55s. The internal layouts of the properties have been redesigned to provide bungalows that will be accessible and warm.

Since its construction in the 1980s, the site’s vacant properties have increased and many became empty. Half of the structures are single person studio apartments which are in need of extending to be brought up to modern building standards suitable for the vary needs of residents. There are multiple communal buildings, the buildings are poorly insulated and the site does not have gas.

______ Our Scope

As Energy Consultants, we assessed existing energy usage using SAP 2012. An energy strategy was then developed with the Architect and Client to meet the project brief and Building Standards requirements. In line with a fabric first approach, the existing dwelling are undergoing deep retrofit, and when combined with the new-build extensions, achieve compliance with the current Building Standards. Different energy upgrades and heating options were modelled to help determine the final solutions.

Additional services provided by Carbon Futures included provision of Approved Certifier of Design (Energy) certification and Building Regulation Compliance through the provision of SAP Calculations. Energy Performance Certificates and Sustainability Labels will be provided upon completion.

______ Details

All the existing properties had a Band E EPC rating.

The fabric U-values vary between what could be achieved in the existing properties and what was required for the extensions. As this was a deep retrofit, the existing homes were stripped back to their bare shell in order to be properly insulated. The existing timber frame walls were insulated with high performance mineral wool, and additional rigid PIR insulation was installed on the inside face of the timber frame, resulting in an external wall U-value of 0.18 W/m²K. The new-build external walls have a similar strategy and achieved a U-value of 0.14 W/m²K

The existing suspended timber ground floors were all insulated to bring the U-value up to 0.23-0.25 W/m²K depending on the Perimeter/Area ratio. All roofs have 450mm of mineral wool to give U-value of 0.09 W/m²K. The properties also benefit from new triple glazed windows and high-performance external doors.

All properties are installed with new Decentralised Mechanical Extract Ventilation (dMEV) systems and new vapour control layers to enable the dwelling to achieve a design air permeability of ≤ 4.5 m³/hm² (@50Pa). Heating is provided through modern High Heat Retention Storage Heaters supplemented with Photovoltaic panels to offset electricity costs. Excess electricity is exported to the grid.

The proposed SAP Ratings post-completion range between 87B and 92A.

The development is designed to achieve Platinum Aspect Level 1 (Direct Greenhouse Gas Emissions), by default of having a Zero Direct Emissions Heating System, and Silver Aspect Level 2 (Energy for Space Heating) under Section 7 (Sustainability) in accordance with funding requirements.

______Project Partners

Wheatley Group, Hub West Scotland, Montagu Evans, CCG (Scotland) Ltd), NBM Construction Cost Consultants, ECD Architects Ltd, Woolgar Hunter, Hawthorne Boyle and Rankin Fraser

______Project Partners

Trust Housing Association, Anderson, Bell + Christie Architects, G3 Consulting Engineers, NBM Cost Consultants and TSL Contractors