The Great Irish Energy Smackdown: Are Apartments Secretly Winning the War on Cold?

Let’s set a scene. It’s a Tuesday in November. The sky is the colour of a sad dishcloth, and the rain is coming down with the kind of passive-aggressive determination only Ireland can muster. You’re in your apartment, wearing three jumpers and a dressing gown that has seen better days. You can feel a faint, ghostly breeze coming from… well, everywhere. Your heating is on, making a noise like a dying badger, and costing you a fortune to produce the ambient temperature of a large refrigerator.

You text your friend. “I am becoming one with the ice age.”

They reply instantly. “Ugh, tell me about it. This house is like a wind tunnel. The dog is wearing a hat. A HAT.”

And then the question hits you. The one that has plagued Irish residents for generations, sparking debates in pubs and over cold cups of tea. In this epic battle against the damp and the dark, who is supposed to be winning? Your apartment, a compact box in the sky? Or their house, a proper, grown-up structure with a front door and a garden gnome?

On the surface, it seems simple. Apartments are smaller, right? So they must be cheaper to heat. But then houses are newer sometimes? And have better boilers? But apartments have people living above and below them, which is like being the jam in a human sandwich, and jam is never cold. Is it?

Welcome, my friend, to a glorious, nerdy, and unexpectedly fascinating rabbit hole. Because the real answer isn’t a simple “yes” or “no.” It’s a wild journey through building physics, baffling statistics, and a few paradoxes that will make you question everything you thought you knew about your own home. We’re going to deconstruct this whole thing, piece by piece, until you become the most informed person you know on the topic of Irish residential energy performance. Ready? Grab a blanket. It’s about to get scientific.

Chapter 1: Decoding the Mystic Scroll (aka The BER Certificate)

Before we can compare an apple to an orange, we need to agree on what a fruit is. In the world of home energy, our universal fruit-definer is the Building Energy Rating, or BER certificate. You’ve probably seen one—it’s that rainbow-coloured label that looks like it belongs on a washing machine, and as mandated by law, it’s required whenever a home is sold or rented in Ireland.

Most of us look at it, see a letter like ‘C3’ or ‘D1’, and think, “Huh. Okay then,” before using it as a coaster. But this little certificate is the key to everything. It’s trying to tell us a story, but it’s written in a language we don’t understand. So let’s learn the language.

What the BER Is (and Isn’t)

The most important thing to understand about your BER is that it’s an “asset rating,” not an “operational rating”.

This is a crucial distinction. Let’s use an analogy. Imagine you’re buying a car. The sticker on the window tells you it gets 50 miles per gallon. That’s its asset rating. It’s a standardised measure of the car’s potential efficiency, based on its engine, its weight, its aerodynamics. It’s the car’s report card.

Now, you buy the car and drive it like you’re perpetually late for the birth of your first child, flooring it at every green light. You’re only getting 30 MPG. That’s your operational rating. It’s based on your actual behaviour.

The BER certificate, as the Sustainable Energy Authority of Ireland (SEAI) explains, rates the ‘car,’ not the ‘driver’. It doesn’t care if you leave the heating on 24/7 or if you shower in volcanic water for an hour every day. It calculates the inherent energy efficiency of the building’s fabric and systems, assuming a standard family living a standard life. It looks at:

• The Building’s Bones: How much insulation is in the walls, attic, and floor.
• The Eyes and Mouth: The quality and type of your windows and doors.
• The Heart and Lungs: The efficiency of your heating system, hot water system, and ventilation.
• The Nerves: The lighting system.

Crucially, it does not include the electricity you use for your telly, your PlayStation, your laptop, or your extensive collection of novelty kitchen gadgets. It’s all about the building itself, which is the only way you can get a fair, like-for-like comparison between your gaff and your mate’s.

The Magic Number: kWh/m²/year

So how does it boil all that down to a single letter grade? It uses a primary metric that sounds terrifyingly complex but is actually quite beautiful: kilowatt-hours per square metre per year (kWh/m²/yr).

Let’s break that down with another analogy. Imagine your house is a giant, slightly leaky bucket. “Energy” is the water you have to constantly pour into it to keep it full (i.e., warm). The BER is measuring how many litres of water (a kilowatt-hour or kWh is just a unit of energy) you need for every square inch (m²) of bucket, over a whole year.

A house with a terrible BER is like a sieve. You’re pouring in buckets and buckets of expensive energy-water, and it’s just gushing out through the walls, roof, and windows. A house with a great BER is like a YETI flask. You pour a little bit in, and it stays warm for ages.

The A-to-G scale simply puts these numbers into easy-to-understand grades.

• A-Rated: The YETI flask. A superhero of a house. Needs less than 75 kWh/m²/yr. It’s so well insulated and airtight, you could probably heat it with a single, angry hamster on a wheel.
• B-Rated: A very, very good house. The target for most government retrofit grants is a B2, which is considered the benchmark for a truly comfortable and efficient home.
• C-Rated: This is the most common rating in Ireland. It’s… fine. It’s the property equivalent of getting a ‘C’ in your Junior Cert maths. You passed, but you’re not going to be an astronaut.
• D & E-Rated: Now we’re getting into leaky territory. These homes are noticeably less comfortable and have higher bills.
• F & G-Rated: The sieve. These are the homes that are actively trying to bankrupt you. A G-rated home can cost ten times more to heat than an A-rated one. It’s a thermal disaster zone.

Now that we speak the language, we can finally ask the question. Who has the better bucket? The apartment, or the house?

Chapter 2: The Main Event – Apartment vs. House (The Efficiency Smackdown)

Alright, the scene is set. In one corner, weighing in with an average floor area of 70 square metres, we have the Irish Apartment. In the other corner, a heavyweight contender at a whopping 166 square metres for a detached version, we have the Irish House. The bell rings. Let the physics begin.

Round 1: The Thermal Envelope

When we look at the pure, unadulterated efficiency numbers—the kWh/m²/yr—it’s not even a contest. Apartments win. And they win by a knockout.

The official data from Ireland’s Central Statistics Office (CSO) is crystal clear. The average apartment requires 184 kWh/m²/yr to run, giving it a solid C2 rating. This is significantly better than any type of house. Semi-detached houses need 193, detached houses need 202, and terraced houses, surprisingly, need the most at 210 kWh/m²/yr.

Why such a crushing victory? It comes down to a concept called the “thermal envelope.”

Imagine it’s freezing outside and you’re trying to stay warm. A detached house is like a lone camper standing on a windy hilltop in a t-shirt. It’s being attacked by the cold from every conceivable angle: all four walls, the floor, and the roof. It’s losing precious heat to the cruel, cold world in every direction. The thermal envelope is basically everything that separates the inside of your home from the great, chilly outdoors.

Now, think about a mid-floor apartment. It’s not a lone camper. It’s a penguin in the middle of a huddle.

Its floor is touching the warm ceiling of the apartment below. Its ceiling is touching the warm floor of the apartment above. It’s probably sharing one or two walls with its equally warm neighbours. The only parts of it actually touching the cold outside world are the front and back walls. Its thermal envelope—the surface area through which it can lose heat—is tiny in comparison to the house.

This is why mid-floor apartments are the undisputed champions of energy efficiency in Ireland, with a staggering 29% of them achieving a top-tier A-rating. They are being passively heated by everyone around them. They are the smug, warm jam in a giant, building-sized sandwich.

The Curious Case of the Cold Terraced House

But wait, I hear you cry. If sharing walls is so great, why are terraced houses the least efficient of all? They share two walls! Shouldn’t they be pretty good?

This is our first clue that there’s a bigger, more powerful force at play here. The problem isn’t the shape of a terraced house; it’s the age. A huge chunk of Ireland’s terraced housing stock is ancient. They were built in an era when “insulation” was just a fancy word for “slightly thicker wallpaper” and “airtightness” was what you achieved by stuffing a tea towel in the gap under the door.

This legacy of old, inefficient buildings drags the average for all terraced houses way down. It’s a statistical ghost from the past, haunting the data. And it perfectly introduces the most important character in our entire story.

Chapter 3: The Real Boss – The Unstoppable Tyranny of Age

Here’s the single most important sentence in this entire article: The year your home was built is a far, far better predictor of its energy efficiency than whether it’s an apartment or a house.

Dwelling type matters, but age is the undisputed, all-powerful emperor of energy performance. A new house and a new apartment are thermal siblings. A new apartment and an old apartment are from different planets.

Think of it like comparing cars again. You wouldn’t compare a 2024 Ford Focus to a 1975 Ford Cortina and say, “Well, they’re both Fords.” The technology, the engineering, the regulations have changed so profoundly that they are fundamentally different machines. It’s the same with our homes. Ireland’s building regulations have been getting progressively, aggressively stricter over the decades. What was considered perfectly fine in 1980 would be considered a thermal crime today.

The data on this is not just clear; it’s jaw-dropping. Let’s look at the percentage of homes that achieved an A-rating, based on when they were built:

• Built 2020-2024: 99%
• Built 2015-2019: 95%
• Built 2010-2014: 36%
• Built 2005-2009: 4%
• Built before 1977: A measly 3%

That’s not a trend; that’s a revolution. The introduction of the Nearly Zero Energy Building (NZEB) standard in 2019 basically made it mandatory for all new homes to be hyper-efficient A-rated machines.

Let’s go back to our leaky bucket metric, the kWh/m²/yr, and see how it plays out across the eras. This is where it gets really wild:

A detached house built between 2020-2024 needs just 38 kWh/m²/yr (an A2 rating).

An apartment built before 1977 needs a staggering 363 kWh/m²/yr (an E1 rating).

Read that again. The brand-new house is almost ten times more energy-efficient per square metre than the old apartment*. The penguin huddle means nothing when the penguins are all wearing mesh vests. Age doesn’t just trump dwelling type; it drop-kicks it into another dimension.

So, if you live in a 1980s apartment and your friend lives in a 2022 house, the reason they might be more comfortable (before we even get to the bills) has nothing to do with apartments vs. houses. It’s because their home is a sleek, modern Tesla, and yours is a beloved, but fundamentally leaky, old Cortina.

But hold on. We’ve established that apartments are more efficient (for their age) and that new homes are more efficient (overall). But does that actually mean they use less energy in the real world? Prepare for plot twist number two.

Chapter 4: The Great Size Paradox – Why ‘Efficient’ Doesn’t Mean ‘Cheap’

Up until now, we’ve been living in the neat, theoretical world of the BER certificate, comparing efficiency on a per-square-metre basis. But our energy bills don’t arrive per square metre. They arrive for the whole, entire lump of a house. And this is where a giant, house-shaped spanner gets thrown into the works.

Here’s the paradox: In Ireland, more energy-efficient homes often use more total energy and have higher bills than less efficient ones.

How is this even possible? It’s like saying the YETI flask costs more to keep warm than the sieve. It makes no sense. Until you factor in one, enormous variable: size.

The data shows a clear and consistent trend: higher-rated homes are, on average, much, much bigger than lower-rated homes. An A/B-rated detached house has an average floor area of 227 m². An F/G-rated one is just 90 m². And as we know, the average detached house (166 m²) is more than double the size of the average apartment (70 m²).

Let’s go back to our car analogy. An A-rated house is like a brand-new, super-efficient luxury coach. A G-rated apartment is like an old, beat-up Fiat 500. The coach has incredible MPG (efficiency), but it’s a massive vehicle. The Fiat has terrible MPG, but it’s tiny. Heating the giant, efficient coach simply requires a much larger absolute volume of fuel than heating the tiny, inefficient Fiat.

The real-world, metered energy consumption data from the CSO proves this beyond a shadow of a doubt. When it comes to total energy use, houses are the undisputed heavyweight champions of consumption.

• Natural Gas: In 2023, detached houses used an average of 12,411 kWh of gas. That’s 87% more than apartments, which used 6,653 kWh.
• Electricity: For homes with electric heating, detached houses consumed a mean of 7,388 kWh in 2023. That’s 77% more than apartments (4,196 kWh).

So, while your friend in their big, modern A-rated house has a more efficient home per square metre, their overall energy bill for heating is almost certainly higher than yours in your smaller, less-efficient apartment. They are paying to heat a ballroom; you are paying to heat a closet. The ballroom is better insulated, but it’s still a ballroom.

There’s also a sneaky psychological factor at play here called the “rebound effect”, a concept related to the historic Jevons Paradox. If you know you live in a leaky, G-rated sieve, you behave accordingly. You seal off unused rooms, you live in a hoodie, and you only turn the heating on when you can see your own breath. But if you live in a big, A-rated palace, you think, “This place is cheap to run!” You crank the thermostat up, heat every single room to a balmy 22 degrees, and generally live like a Roman emperor. A portion of the efficiency gains are “spent” on extra comfort, leading to higher-than-expected bills.

Chapter 5: So, Who Actually Wins? And What Can You Do About It?

We’ve been on quite a journey. We’ve decoded mystic scrolls, witnessed a penguin huddle, travelled through time, and unravelled a great paradox. So, let’s finally answer the question: in the great Irish energy smackdown between your apartment and your friend’s house, who wins?

The answer, in classic Irish fashion, is: “Well, it depends.”

Let’s have a final summary of the winners in each category:

• The Efficiency Award (per m²): The Apartment. Thanks to the penguin huddle effect, apartments are inherently more efficient at holding onto heat, all other things being equal.
• The Energy Bill Award (Total Cost): Also the Apartment. Simply by being smaller, apartments require less total energy to heat, even if they are less efficient per square metre than a new-build house. Size matters most when the bill arrives.
• The “Who Is Actually Warmer and More Comfortable” Award: The Newest House. This is the big one. The unstoppable power of modern building regulations means that a new A-rated anything will provide a level of comfort that an old D-rated anything can only dream of.

The real takeaway is this: stop comparing your apartment to a “house.” It’s the wrong question. Start comparing your home to other homes built in the same era. If you live in a 2005-build apartment, its true rival is a 2005-build house. And in that fight, your apartment’s efficiency is likely superior.

The Real Enemy: Heat Loss

Regardless of where you live, if your home was built before, say, 2015, the chances are it’s leaking heat. It’s wasting your money and wrapping you in a permanent state of low-grade chilliness. But the good news is, you can fight back. And the strategy is simple.

Experts at the International Energy Agency and here at home talk about a “fabric first” approach. This is just a fancy way of saying, “For the love of God, put a proper coat on your house before you spend a fortune on a fancy new heating system.” There is no point installing a state-of-the-art €15,000 heat pump if all that lovely, efficiently-produced heat is just going to ghost you through the attic five minutes later.

You need to fix the leaky bucket. And the biggest holes are almost always the same:

1. The Attic: Heat rises. It’s a law of physics. In an uninsulated house, up to 30% of your heat goes straight up and out through the roof. Insulating your attic is the single most cost-effective upgrade you can make. It’s the energy efficiency equivalent of eating your vegetables. You just have to do it.

2. The Walls: The next biggest hole is your walls, which can account for another 30-35% of heat loss. If you have cavity walls, you can get them pumped with insulation. If you have solid walls (common in older properties), you have two main choices: insulate them from the inside (dry-lining), or from the outside. For many homeowners, tackling external wall insulation in Dublin is a game-changer, as it wraps the entire building in a seamless thermal blanket without disrupting your life inside. You can learn more about this process in this ultimate guide to external wall insulation.

Only once you’ve plugged these giant holes should you look at upgrading windows and your heating system. By making your home’s fabric robust and airtight, you make every other investment work ten times harder.

So, the next time you’re texting your friend from inside your blanket fort, you’ll be armed with knowledge. You’ll know that your apartment is probably more efficient, but their house is probably newer, and that’s why they might be warmer. But you’ll also know that both of you are probably living in leaky buckets. And you’ll know exactly how to start fixing them.

The war on cold isn’t about apartments vs. houses. It’s about well-insulated homes vs. poorly-insulated ones. And it’s a war you can win.

👉 If you’re ready to stop heating the sky above your head, the first and best place to start is your attic. Check out how to get it sorted here: https://retrofitdublin.ie/attic-insulation-dublin