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Energy-Efficient Transformation: A Deep Retrofit Journey

Fig. 1 Before and after


Embarking on a transformative journey in March 2023, we undertook the deep retrofitting of a 1980s bungalow nestled in the charming town of Kinsale. Completing most of the work by June 2023, this project aimed at significantly enhancing the energy efficiency of the home while minimizing disruptions to its interior.

Fig. 2 Interior Issues with moisture ingress, ventilation and thermal bridging

Exterior Focus:

Our approach centered on external improvements, starting with a 300 mm excavation around the house perimeter to address water ingress and insulating below the slab to prevent flanking heat loss. Removing deteriorating bays plagued by thermal bridging and moisture issues, we meticulously ensured the alignment of the new 400 mm Ecocel cellulose insulation with the 200 mm external insulation to eliminate thermal bridges.

Fig. 3 Perimeter Excavation and new thermal blocks and thermal isolator bay supports

Roof Insulation Strategy: Installing insulated rigid insulation between roof rafters, extending 400 mm, created a seamless connection for the Celulose insulation blown into the attic. Weather-tight tape secured this insulation to the external insulation, preventing weak points and ensuring optimal thermal performance. This meticulous strategy allowed for the subsequent installation of 400 mm of Ecocel insulation in the attic, post LED spotlight and mechanical ventilation heat recovery system installation.

Fig. 4 Perimeter eave insulation maintaining 50mm of ventilation to cold roof above 400mm of Ecocel insulation

Window and Door Upgrades:

All windows were replaced with Munster Joinery's passive windows, while new projected bays cantilevered off existing block walls. Closing the cavity between block leafs and weather taping windows to the external block wall, we adopted a build tight build right strategy. The replacement of external doors and the encapsulation of the boiler house within the thermal envelope further enhanced the home's energy efficiency.

Fig. 5 Window Installation and air tightness internally

Video 1. Weather Tightness detailing with Prodomo thermal isolating blocks

Active Systems Integration:

Following the passive-first approach, we reduced the building's energy demand through improved insulation before introducing active systems. These included an air source heat pump, replacement low-temperature radiators, a mechanical ventilation heat recovery system, and south-facing photovoltaic panels in the garden.

Fig. 6 Before heat loss and post heat loss: External temperature 3C

Performance Assessment:

Thermal imaging conducted in December 2022 and repeated in December 2023 showcased significant reductions in heat loss. Even during external challenges such as high winds and cold temperatures, the clients experienced enhanced comfort within their home.

Fig. 7 Better Energy Community Grants applicable to this project

Financial Considerations:

Ashgrove Renewables facilitated the client's application for a grant under the SEAI Better Energy Community Scheme, allowing them to access €32.5k in grants to offset the project's capital cost. While the investment was significant, it's crucial to recognize that the retrofit not only improved energy efficiency but also extended the building's lifespan by another 45 years, addressing the aging building fabric. At a time when energy costs were doubling the energy conservation measures in this house how to insulate the clients from future energy price increases and energy shocks.

Fig. 8 Post retrofit project including landscaping and new LED lighting


This comprehensive retrofit not only enhanced the energy efficiency and thermal comfort of the 1980s bungalow but also contributed to its longevity. The synergy of passive and active systems, coupled with strategic insulation measures, has transformed this house in Kinsale into a sustainable and comfortable modern dwelling.

In the picturesque town of Kinsale, where the allure of new construction often beckons, this retrofit project stands as a testament to the untapped potential residing in existing structures. While some may opt for the demolition of older buildings, discarding their embodied energy and carbon sequestration capabilities, our endeavor showcases a different narrative.

Through the careful modernization of this 1980s bungalow bliss, we've proven that existing buildings can not only rival but surpass the sustainability and comfort of their new counterparts. This transformative journey emphasizes the value of preserving and upgrading, not just for the building itself but for the environment and community as a whole.

Many thanks to Mannix Building and Renovation for their excellent work on this project. Many thanks to our patient and supportive clients.

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