On the Path to a Sustainable Home in Ireland

November 19, 2022 12-minute read

In this post, I explain how we have gone about upgrading our home to become a sustainable home with a top rating. As well as experiences along the way.

But first a disclaimer: this guide is for retrofits and incremental change. What we did might not be entirely suitable for others. Also, note that many of the organisations, initiatives, metrics and thresholds listed below are Irish.

The beginning

We bought our home back in 2015. It is a traditional, modest Irish 4-bed bungalow, built in the late ’90s.

When we arrived, two important - and arguably fundamental - upgrades had already been carried out in the form of attic insulation and pumped walls (beads).

However, there was still plenty of scope for improvements, including:

Double-glazed windows and doors with the seals almost gone
Inset electric fireplace in the living room with an open chimney
Open fireplace in the kitchen

From an Irish standpoint, the house was listed with a BER rating of D1 at the time of purchase.

The energy rating of a home

In Ireland, the energy consumption of a home is rated with a Building Energy Rating (BER), which is a scale to estimate a home’s energy performance. The BER and underlying processes are managed by the Sustainable Energy Authority of Ireland (SEAI).

The BER rating scale is A to G (with gradual numbers 1-3 per letter included) with A best and G worst performing in terms of the energy performance of a building.

It is a legal requirement that a home is BER rated for sale or rental. The BER rating is generally valid for 10 years following issuance.

Note that energy performance on the certificate is rated across two dimensions:

kWh/m2/yr, i.e. how many kilowatt-hours of energy are typically needed per square meter per year in the home. The energy calculation includes space heating, water heating, ventilation and lighting. This is the metric that decides the BER rating, e.g. a D1
kgCO2/m2/yr. In other words how much CO2 (labelled a greenhouse gas) is needed - again per square meter of the home - for the abovementioned energy consumption per year

One might argue that the kgCO2/m2/yr metric is more important to track from a climate change and sustainable living perspective.

For instance, to meet home heating demands (a large part of a home’s energy consumption), one could use heating oil (kerosene) to heat the home. Alternatively, one could meet the heating demands with a heat pump and buy electricity from a 100% renewable energy provider like SSE Airtricity or Energia.

The two different energy sources for heating the home have completely different levels of CO2 emissions.

It is important to note that the abovementioned metrics are calculated based on a model. The BER assessor answers a questionnaire based on the type of home, number of floors, fabric, ventilation etc. The answers are slotted into the Dwelling Energy Assessment Procedure (DEAP) software by the BER assessor.

Note that the DEAP model changes from time to time. Therefore, the BER assessment is versioned. For instance, our BER certificate has a version identifier in the bottom right corner: DEAP Version: 4.1.0.

It is important to note that there is one additional metric, which must be calculated before a heat pump installation commences to unlock the SEAI heat pump grant; the heat-loss indicator (HLI). The formula and threshold are HLI <= 2W/Km2 (or < 2.3Wm2K with certain conditions attached), i.e. less than 2 Watts per Kelvin multiplied by square meter. The HLI is a measure of the insulating properties of fabric and ventilation heat loss. The formula for calculating the HLI is closely related to the formula for determining the U-value (e.g. windows), again a measure of the insulating properties of the fabric.

More information about the HLI and related metrics, the role of the technical BER assessor and the process can be found in the SEAI document Technical Assessment Process for Heat Pump System Grants.

Getting started

Arguably the best way to approach a sustainable retrofit is to look at the project holistically. Before getting started, find a suitable path of incremental changes that you wish to take.

This is important because some initiatives might not work optimally with others.

For instance, installing a solar hot water heater and then later a Solar PV system might not be optimal (e.g. roof space) because getting either a Solar PV diverter for hot water (using excess electricity to heat water) - or indeed installing a heat pump (for both hot water and heating) - would achieve the same outcome with just a single rooftop system.

Therefore, the best advice I can give to get started is to find a knowledgeable, SEAI-certified technical BER assessor and have them come out and do an assessment.

The most important aspect of the assessment is arguably to get an understanding of where the house stands in terms of BER rating and heat loss.

But also, BER assessors can be sources of information about what upgrades can be done and also what order to perform them in.

However, bear in mind that not all BER assessors are created equal. For instance, for the first BER assessment we got done in 2018 a junior assessor who I’m not even sure was fully qualified turned up. The actual qualified BER assessor was hiding away in the office and I only got to speak to him over the phone once.

The junior assessor gave some awful advice for our circumstances, including:

I don’t think your home will run on a single heat pump and I encourage you to keep the oil heating system as a backup for cold days
You should not upgrade the old double-glazed windows for new windows without first getting an external envelope facade of insulation (a very costly option over upgrading windows)

Both statements were untrue in our case. And the sad fact is that homeowners make decisions on the back of bad advice.

On both counts, we chose to ignore the advice after doing our research. But the silver lining was that it encouraged us to substantially research the subjects.

However, we got a thermal imaging scan out of the assessment, which was carried out on a cold day (as it should be). This gave us an overview of cold bridges in the house, which allowed us to decide if more insulation was needed (it was not).

Later, we found a much more knowledgeable BER assessor who we have stuck with for 3 assessments so far.

Some considerations about finding a BER assessor that is right for you:

Make sure it will be the actual BER assessor that creates the report who arrives at your front door to do the assessment
BER assessors are supposed to be impartial so be wary of BER assessor recommendations made by vendors
Prepare for the visit and write down questions you would like answered. Make sure the BER assessor is made aware in advance that you will have questions and can allocate some time accordingly
Ask the BER assessor to detail what initiatives are suitable for your home and what order to do them in; but again, Trust but Verify with your research and ask questions

Once the assessment is done you should expect the following from the BER assessor within a few days/weeks following the visit:

A new BER certificate (ask for a PDF copy to be sent to you)
A report with specific recommendations for the next set of improvements to make
A heat-loss indicator (HLI) if a heat pump is considered

Our journey

After the initial BER assessment, we started researching the different options and their suitability to our circumstances.

We came up with a plan of what options we wanted and a rough order of which to do them.

In many ways, we started with the options that had the most impact for the least cost (assuming that the options wouldn’t clash with later options).

Therefore in our case, the order was as follows. We carried out this work in 2017-2018.

Replace the open fireplace in the kitchen with an inset stove. It made a huge difference in heat loss and provided much better comfort and efficiency when the stove was alight
Remove the electric fireplace in the living room and permanently block up the chimney. Again, this made a big difference in heat loss
Replace certain air vents with closable vents so that we can control airflows during high winds and storms
Replace double-glazed windows with triple-glazed passive house-rated windows and doors. The indicator of window and door efficiency is measured in U-value (W/m2K), which is a measure of how effective a material is as an insulator. Note that U-values are typically quoted separately for the window/door and the frame. A lower number means better efficiency

The above changes resulted in an improvement of the BER rating from a D1 to a C2. It also improved the heat-loss indicator (HLI) of the house from 2.02 to 1.94 (less is better).

The HLI, now <= 2.00, therefore crossed the point where we could get a heat pump with SEAI grant without further testing or assessment needed (such as an airtightness test).

Next, we installed a heat pump system and got rid of the old oil-fired system. We researched and spoke to the different businesses that offer heat pumps. The outcome was that we also needed the radiators replaced.

We went with the one provider who offered a one-stop shop for project management and stood over the installation. We went through several iterations of planning with them and long waits but finally, in January 2022, we had the heat pump and new radiators installed.

This turned out to be good timing as the Ukraine war started shortly after and heating oil prices skyrocketed (practically tripled).

We had a new BER assessment carried out at this point and the rating improved from a C2 to a B1.

As the Ukraine war continued the electricity prices started increasing substantially from 14c/kWh to 41c/kWh (including discounts) in 6 months.

In September 2022 we therefore finally decided to do something about it and ordered a 9kW Solar PV system and a 15kW battery system. We chose the battery option because we have a heat pump and because I work from home virtually all of the time.

This system was installed in October 2022. The output of the system is immense and even during the October and November months, we are generating electricity to meet approximately 50-60% of our demand. This includes an electric car.

Afterwards, a final BER assessment was done and the rating improved from B1 to A1 (the highest rating).

Not only did the rating improve to an A1 but as a result of the size of the Solar PV system the following two numbers ended up becoming negative:

-40 kWh/m2/yr (-4800 kWh per year for the whole house)
-5.66 kgCO2/m2/yr (-680 kgCO2 per year for the whole house)

In other words, according to these numbers we are overproducing electricity to provide heating and lighting in the house. We can use the excess electricity (4800 kWh) for cooking, TV, electric car etc. instead.

Our learnings

Before starting, get the facts (assessments) that will allow you to make sound decisions
Doing your research and becoming familiar with what different options and solutions solve for, how they work and what their constraints are, definitely pays off
Try to avoid engaging with businesses that are not one-stop shops for a given solution. An overarching goal on our part was to reduce the scope for contractors and vendors blaming each other for issues. We hired only one-stop shops for windows, for the heat pump and radiators and finally for the Solar PV and battery system

Achievements

Doing all of these upgrades does not just provide a feel-good factor in terms of reducing our CO2 footprint in the world.

There are sound financial and comfort reasons for doing the upgrades. Fixing the fireplaces, replacing the windows and all of the other smaller changes allowed us to reduce the heat loss in our house. And as a result, we save money and have better comfort.

The heat pump system is always on and ensures that we have a nice, stable temperature in the house day and night with no need to continuously set timers, schedules etc. We have the system set for 19-20C throughout the day and 17C at night. It just works.

The solar PV and battery system is saving us a lot of money. And in today’s electricity price terms the system is estimated to repay itself in 7 years. This will provide us with another 20+ years of “free” use after. In other words, it’s a great investment.

Costings & grants

The following table provides an overview of the cost associated with the work we carried out over several years. The net, nominal cost (ignoring inflation over the years) for all of the work is just below €50.000,- after subtracting grants. This brought us from a D1 BER rating to A1, which also resulted in a negative (in a good way) CO2 footprint.

Works	Year	Cost	Grant
Inset stove	2017	€2.000
Windows/doors	2018	€11.500	€1.500
Block chimney etc.	2018	€1.000
Heat pump/radiators	2022	€24.000	€6.500
Solar PV & battery	2022	€20.500	€2.400
3 x BER assessments	-	€1.000	€200
Total	-	€60.000	€10.600

Several grants for homeowners are available with the Sustainable Energy Authority of Ireland, SEAI. Grants not listed above include support for attic insulation and to pump external walls.

What next

Even while we have lived in the house for over 7 years, we have noticed that Ireland is getting wetter weather-wise and as a result air humidity is getting worse. This has led to issues in the wintertime where mould has started forming in corners in a couple of the bedrooms. We have managed to keep on top of it by washing it down with a strong bleach solution.

But ideally, we would like to avoid this problem altogether. We can avoid it by installing a ventilation and heat recovery system. The idea is to provide a source of fresh air, to dehumidify the air inside and finally to also keep most of the heat indoors in the process.

A bonus is to get a system that has a summer bypass that allows for cool air to flow in from the outside at night during particularly hot weather.

However, the house needs to be assessed for suitability for a ventilation system. The effectiveness of the system comes down to the air-tightness of the house.

We will therefore need an air tightness test. The assessment measures how much air (and therefore heat) escapes at a given pressure. There are two different methods to test this:

Air changes per hour at 50 Pascals of pressure
Air permeability rate per hour at 50 Pascals pressure (threshold: <= 5 m3/hr/m2)

We will provide more details as we know more.