Type of construction: 2D facade renovation and 3D volumetric addition
Typology: Two-story semi-detached houses, circa 80m2
Owner: Local Authority – Westmeath County Council
Construction systems: Concrete floors, masonry block cavity walls with timber intermediate floor and roof
Location: Ireland, Athlone
The Irish case study is a typical Irish two 1970s social houses constructed of masonry block cavity walls with solid concrete ground floor, timber first floor and cold-vented attic timber roof. The retrofit incorporated modular wall panels and extension systems grounded in environmental and circular design principles. The original thermal performance of the construction was poor but had been previously upgraded with attic insulation and pumped insulation to the cavity. The original houses where heated by solid fuel open fires but were later upgraded with central heating from solid fuel and oil boilers. However, the energy rating of the houses remained poor and the challenge was to provide a deep energy retrofit of the dwelling involving an advanced thermal upgrade to the envelope via circular modularised solutions including upgraded space and water heating with ventilation systems and renewables.
Both houses underwent similar fabric upgrades. However, each had a bespoke system and renewables upgrade. The fabric upgrade entailed a conventional external wall insulation (EWI) system on the rear and sides, the replacement of windows and doors with triple-glazed units, and the addition of 2D modular wall panels on the front to achieve a targeted U-value of 0.2 W/m²K. A porch, showcasing a 3D ‘pod’ solution, was added using a similar modular construction. One house, already equipped with a heat pump, was fitted with mechanical ventilation with heat recovery (MVHR) and a photovoltaic (PV) array. Conversely, the other house had its traditional solid fuel range swapped for a biomass pellet stove boiler, complemented by a PV array and a demand control ventilation system. Monitoring of energy consumption, air quality, and thermal comfort in both houses is ongoing to evaluate the effectiveness of these changes, with positive interim results. The project’s key feature was the development of the modular construction system, which integrated low-carbon and circular solutions. The Irish team, comprising TU Dublin as the lead/research partner, along with industry partners COADY Architects and Vision Built, adapted an existing light gauge steel structural wall system into a demountable, pre- finished wall panel embodying circularity principles.
Find plans, sections and technical drawings here (Credits to TUDublin, COADY Architects, Vision-Built).
Read more here.
We met the following results in the Irish Athlone Case Study
Case specific outcomes:
This type of intervention can support revised approaches to deep energy retrofits based on a systematic industrial scale solution, resulting in improved occupant comfort and health, increased space and utility, improved circularisation of production and use and reduced environmental impact.
There is also likely to be positive impacts in real estate value and a shortening of payback time of renovation, representing also a commercial and business opportunity manufacturing and construction companies who can foster this type of strategy.
Case specific profits:
Case specific impact indicators:
The design performance of the energy retrofit was estimated via calculations from the Irish national energy rating assessment tool DEAP (Dwelling Energy Assessment Procedure), which is use for production of EPC’s. This showed a significant difference in the performance of the pre-works dwellings and a proportional energy reduction from the retrofit with the house with heat pump going from B3 to A2 and the house with original solid fuel boiler going from E2 to B1. Comparing these assessments to interim results from energy monitoring has indicated a significant performance gap between the asset based energy rating and actual energy use, both pre and post works, especially for the poorer performing dwelling. The monitoring of thermal heat transfer across the existing and retrofitted wall has also shown a significant performance gap between both conventional U Value methods and defaults values used with the DEAP method and reality, with the thermal performance of the wall being poorer than calculated under U value method and significantly different to DEAP defaults, which again impacts on the performance gap.