Friday 20 September 2019

Planning a phased retrofit of your home is cheaper, more energy-efficient and less disruptive in the long run

Planning a phased retrofit of your home is cheaper, more energy-efficient and less disruptive in the long run. John Hearne explains how to refurb your house to make it energy fit and cut your energy bills.

Mariana Moreira and Art McCormack of MosArt architects took a phased approach to retrofitting their Wicklow home. Photo: Frank
Mariana Moreira and Art McCormack of MosArt architects took a phased approach to retrofitting their Wicklow home. Photo: Frank McGrath

John Hearne

If you're considering a refurb, if you're thinking about dry-lining your walls, or changing your windows, or getting a new kitchen installed, stop right there. Don't do anything. Yet.

Architect Brendan O'Connor of Abode Design ( in Dublin says that as many as half the people who call him looking for advice have already done quite a bit of tinkering with their houses, much of which actually has to be undone afterwards.

The rear of the house.
The rear of the house.

Why? He explains that a house loses heat in two ways. The first we all know about. Poorly insulated walls, roof and floor allow heat to be conducted through the building envelope and away from where it's needed. There's less awareness, however, of the second way that your house loses heat - through air leakage, and that tends to be a more significant issue in most of our homes. Achieving a high degree of air-tightness is central to making any house easier and cheaper to heat.

And this is where 'deep retrofitting' comes in. It's a process that involves the complete overhaul of the energy efficiency of a home, it comes at a price but it also creates big savings over time.

"So many people do work but don't look after the air-tightness," says O'Connor. "Maybe they've dry-lined but didn't attend to the vapour control layer, or draught proofing. The end result is that the house stays draughty, but it has a nice finish. It looks great, but doesn't perform."

Achieving air-tightness in a retrofit requires careful detailing, which will be dependent on the form of build. In timber frame houses, for example, an air-tightness membrane, together with proprietary tapes and adhesives, is frequently used to create the airtight layer.

The front of the original 1960s bungalow.
The front of the original 1960s bungalow.

No matter what your project, seeking professional advice is vital, as is putting together a well-thought-out plan. Taking a piecemeal approach to refurbishment can often leave you with all the cost and none of the comfort.

The next point to make is that no matter how meagre your budget, there are almost always steps that can be taken to make your home more comfortable and cheaper to heat.

Installing a lagging jacket on your hot water cylinder, sealing open chimneys, draft proofing doors and windows and switching to low-energy lighting will all have a significant impact on either comfort levels or costs. These are the one-size-fits-all measures. Easy and cheap to do, and applicable to almost any house type.

At a level up from these measures, are the 'shallow' retrofit solutions, many of which are grant-aided under the Sustainable Energy Authority of Ireland's (SEAI) Better Energy Homes scheme. This includes insulating attic and cavity walls, upgrading heating controls, boilers and so on. The applicability of these measures will depend to a large extent on your house and build type, the age of your boiler and so on.

The next level is the 'deep' retrofit, such as the project detailed in the accompanying piece. These include the range of high-impact measures that transform draughty, poorly insulated buildings into high-performance, modern houses.

Deep retrofits don't come cheap. One solution is to stagger the work, to create a long-term plan in which that transformation is phased over 10, 15, even 20 years.

That's exactly what Mariana Moreira and Art McCormack did when they set out to retrofit their 1960s-built, 1990s-refurbished family home - Stella Maris - on an exposed hillside in Co Wicklow. Both are architects with MosArt in Wicklow.

"I can see the North Pole from here," says McCormack, "or at least that's what it feels like when the wind blows from the north." The wind whistling through the house - carrying all the heat away with it - was what prompted the need for the retrofit in the first place.

Adopting a phased approach was all about making the works affordable. And, as Moreira points out, by front-loading the work that will deliver the highest energy savings, those reduced running costs free up resources that can go toward future works.

"It's estimated that 80pc of retrofits in Germany are completed on a phased basis," says Moreira, "so there is a need to develop a good strategy showing how to do this in a proper way."

To that end, developing a thoroughly detailed plan, which specifies the full scope of the works across all phases, is vital.

In Stella Maris, McCormack and Moreira planned three phases. The first, completed two years ago, centred on retrofitting the roof and northern elevation, as well as the installation of a Heat Recovery Ventilation System (HRVS).

The second phase, due to start this month, will involve the retrofit of the east gable elevation. An intermediate phase will follow next summer comprising mainly of internal works, including the replacement of the original open fire with a wood-burning stove.

The final phase, due within two to three years, will see the completion of the remaining south and west elevations, together with a 'modest' extension facing south.

Despite the fact that this is a major refurbishment, the family has not had to move out at any stage. This is because most of the works have been completed on the outside of the structure. External wall insulation - heavily favoured by many passive house designers and builders - wraps the structure in a blanket. Roof insulation was installed by taking off the tiles and working down from above. The necessity of replacing windows during the upcoming phase will be disruptive, but careful scheduling will preclude the need to vacate.

There are disadvantages to the phased approach, of course. You say goodbye to builders only to welcome them back a year or two, or three, later.

For McCormack and Moreira however, that's a small price to pay for the transformation the works have already delivered. And that's not just about making the house easier to heat. It's also about a dramatic improvement in air quality.

"Before we did the works, you'd feel the stale air in the morning. Summer or winter, I was opening windows constantly because CO2 and humidity levels were so high. I don't have to do that anymore. The air is fresh all the time."

If you're going to achieve high levels of air-tightness, it's vital to deliver an appropriate ventilation system. In Stella Maris, the first phase of the works included the installation of a mechanical heat recovery ventilation system. This works by removing the heat from exhausted air, and using that heat to boost the temperature of the incoming fresh air.

Now to the critical issue - payback. If you go to the trouble and expense of giving your home a makeover, at what point do the energy savings compensate for the works done?

Brendan O'Connor says that his retrofit clients invariably tend to be disappointed when he presents them with payback data.

"Usually, when I've worked out payback, it tends to be around 25 years, rather than a nice seven-year timeframe that you'd like to see. But clients never make decisions based on payback alone. It's comfort, it's doing it right, it's an end to crazy bills."

He points to a recent deep retrofit project which he completed at a cost of €260,000. That included a variety of non-energy measures, including an extension, finishes and sanitary ware. Strip those out and the total cost of energy remediation came to around €100,000.

"It's a big outlay, but thanks to those works, the total annual energy costs fell from €3,200 to under €1,000."

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