What is Deep Retrofit?
What is involved in a Deep Retrofit?
People are increasingly aware of the need to retrofit their homes, yet there is very little information available on what deep retrofit means in practice. Here our Retrofit Advisor David Flannery (pictured left), explains some of the features and benefits of a deep energy retrofit.
To create a truly energy efficient, warm and healthy home we need to understand how the house works as an interrelated and interdependent system. Draughty doors will draw heat from your home no matter how efficient your heating; installing energy efficient windows can lead to condensation and mold if the house is poorly ventilated. Even in a well-insulated house, a room might be cold if the heating system is badly designed.
A deep retrofit takes a whole-house approach to energy in the home by looking at the overall effect of a combination of the most appropriate energy measures. The aim is to achieve an improvement in energy efficiency towards the standard of near zero energy, while ensuring that these measures work together successfully, long-term.
Deep retrofit can also be easily understood in terms of what it isn’t. It is not an energy upgrade based on an energy measure or two, often known as a shallow retrofit, or a piecemeal approach taken over time. In a deep retrofit, single measures are not discussed in isolation, but in terms of how they contribute to the whole-house solution. For example, a ‘fabric first’ approach to insulating the walls of a home (external, internal or cavity insulation) is good advice for any retrofit project but raises the question- how much insulation is enough insulation? In a deep retrofit the right insulation levels are determined by ‘modelling’ the finished house, using advanced DEAP (Dwelling Energy Assessment Procedure) software analysis, to assess how it will perform over time.
By using this advanced modelling, the effect of every energy measure being proposed is precisely calculated and weighed for value-for-money to achieve the best solution. Insulation levels, the size of a solar PV system, the u-value of windows and doors, the radiator size and heat pump size; all of these are calculated to produce an overall result in line with the energy target. This analysis may conclude that the current windows are performing just fine so long as insulation and air tightness is improved, or that that double glazing or even triple glazing is required to reach the standard, and so on.
So far, so scientific. But there’s more to a deep retrofit than achieving the best standards of energy performance. Throughout the process ‘non-energy benefits’ are given high priority so that the retrofit includes as many health and comfort benefits as possible. Comfort is directly related to energy efficiency and insulation. Improved air quality comes from introducing intelligent ventilation in a home where ventilation was previously poor or non-existent. These are examples of the positive overlap of energy efficiency and quality of life benefits.
How much does it cost?
The cost of a deep retrofit remains high when compared to a shallow retrofit. Average costs prior to grant funding range from €35,000 to €75,000, sometimes more. Grants of up to 35% maybe available from SEAI via SuperHomes.
A deep retrofit approach tends to be more attractive in certain circumstances, such as when:
- an older house is undergoing wholesale renovation
- an old inefficient boiler is coming to the end of its life
- a house is so poorly performing that a shallow retrofit is not a realistic option
- indoor air quality is poor (evidenced by mold, dampness, unpleasant smells etc)
- the house is currently rated reasonably well, C3 or D1, and so the cost of reaching A3 is comparatively low
- homeowners are likely to experience ongoing higher heating costs because they will be spending more time in the house (retirement, working from home) and will require greater comfort
What do homeowners think?
Feedback on the SuperHomes programme confirms a very high satisfaction rate for homeowners who have undertaken a deep retrofit, with savings on energy costs running at over 70%. The Superhomes 2.0 project, led by full-time researchers at Limerick Institute of Technology, continues to carry out ground-breaking research into optimising heat-pump and solar PV technology in the Irish context, so we can expect further improvements over time, for both existing and future deep retrofit homes. The project also notes an average reduction in carbon emissions of between 60%-80%, which will drop year-on-year as our electricity network becomes cleaner and greener, bringing homes in line with the Paris agreement to limit climate change.