The focus of the 2014-2015 Springboard-funded Postgraduate Certificate in Digital Analysis & Energy Retrofit programme was a study of a archetypal 1930s Dublin Corporation council house which we called ‘Crumlin Cottage’. Each student was required to develop a deep energy retrofit design proposal for a terrace of six houses representing three conditions. The project performance requirement was 45kWh/m2a, the Nearly Zero Energy Building (NZEB) rating.
With over 10,000 such houses in Dublin, the plan was to develop a number of cost optimal solutions which would allow for industrial scale retrofit of these ubiquitous typologies, addressing all of the problem areas by extensive digital modelling, detailed construction drawings and specifications, sustainability assessment and cost optimal calculations.
We found that these are surprisingly complicated buildings to retrofit to any energy standard and particularly fraught with problems related to mould growth. Almost any standard retrofit measure will result in making the present surface or interstitial condensation risk worse than it is already, which is a breach of building regulations. Hundreds of these houses have been retrofitted, some with grant support, but we found that none of these were likely to comply fully with building regulations, particularly in relation to surface condensation risk.
For example, only one, highly specialised, insulation product was found to be capable of addressing the complex thermal bridge at the party wall below the raised collar.
At a public meeting held in Cabra Library, a venue surrounded by such housing, which was organised by DIT to disseminate the findings of the study, occupiers who had undertaken upgrades all reported mould occurrences soon after the works were complete. Both owner-occupiers and council tenants reported the same post-retrofit mould issues. This reflected the predictions of the digital modelling carried out by the postgraduate students.
The cost optimality results were also enlightening with extension one of the most cost optimal retrofit measures that could be employed because it eliminated the need to insulate the ground floor slab. Extension also increased the value of the house and improved its sustainability rating. These houses have a total floor area of less than 75m2 spread over two floors, so it is rare to find one that hasn't been extended.
Prefabricated retrofit solutions were favoured by some students because of the limited number of house types (3) and the extreme replicability of measures given that all houses were essentially cast in concrete using the same shuttering with little dimensional variation.
Linear thermal bridge modelling proved to be essential in these retrofits for proving compliance with building regulation, however, the cost of modelling all 26 linear thermal bridges involved in each house would cost over €10,000, a service provided free to the public by the students on the course through their posters.
Sixteen project designs were produced by a class of architects, engineers, surveyors and architectural technologists using a variety of digital modelling and environmental design software applications.
These are selected posters of the ‘Crumlin Cottage’ projects: