Open-plan kitchen and living areas are brilliant to live in. They feel light, spacious and sociable. But when summer arrives and the sun starts beating through wide patio doors, they can quickly become the hottest room in the house. I’ve lost count of how many homeowners in Kent and Surrey have told me their beautiful extension is unusable by mid-afternoon in July.
If you’re considering air conditioning installation for a large open space, it’s important to understand that cooling these rooms properly takes a bit of planning. It’s not just about putting a unit on the wall and hoping for the best. The size of the space, the layout and even where you sit in the evenings all make a difference.
Here’s what you need to know to create a cool open plan living space that actually stays comfortable.
Why Open-Plan Rooms Are Harder to Cool
On paper, it might seem simple. Bigger room equals bigger air conditioner. In reality, open-plan layouts behave differently to standard lounge or bedroom spaces.
First, the volume of air is much greater. You’re not just cooling a floor area, you’re cooling air up to the ceiling height which in extensions is often higher than the rest of the house. Warm air rises and collects at the top, especially in rooms with vaulted ceilings or rooflights.
Second, kitchens produce heat. Ovens, hobs, boiling kettles and even fridges all add background warmth. I’ve stood in plenty of open-plan kitchen diners in Dartford where the cooking alone adds a few extra degrees on a warm day.
Third, these rooms often have large glazing areas. South or west-facing bifold doors in places like Epsom look fantastic but they let in a huge amount of solar gain. Blinds help, but they don’t solve everything.
And lastly, the air has nowhere to be contained. There’s usually a hallway, maybe a snug area and sometimes stairs leading off. Cool air can drift away if the system isn’t designed correctly.
Choosing the Right AC Capacity for Open-Plan Areas
This is where professional sizing matters. I often get asked if a standard 2.5kW or 3.5kW wall unit will do the job. For most open-plan spaces, the answer is no.
Capacity depends on:
- Room size and ceiling height
- Amount of glazing and direction it faces
- Insulation levels
- Number of occupants
- Kitchen heat gains
A typical open-plan kitchen and living area of 35 to 50 square metres often needs something in the 5kW to 7kW range, sometimes more if there’s a lot of glass. But it’s not guesswork. We calculate it properly.
Oversizing is just as problematic as undersizing. A unit that’s too big can short cycle, switching on and off repeatedly which wastes energy and doesn’t dehumidify properly. A unit that’s too small will run flat out and still struggle.
Best AC Types for Large Open Rooms
Not every type of air conditioning suits a large open space. Here’s what tends to work best.
High-Wall Split Units
These are the most common option. A single powerful wall-mounted unit placed correctly can cool a large area effectively. Modern designs are sleek and quiet and many homeowners are surprised at how unobtrusive they look once installed.
The key is location, which I’ll come on to shortly.
Multi-Split Systems
If the open-plan area has distinct zones, for example a kitchen at one end and lounge at the other, a multi-split system with two indoor units can give more even coverage. Each indoor unit connects to a single outdoor condenser.
This setup works well when one single wall unit would struggle to throw air evenly across the whole space.
Ducted Systems
In larger refurbishments or high-end projects, ducted air conditioning can be installed in ceilings. Supply grilles are discreet and airflow is distributed more evenly.
This is often considered during wider projects such as extensions with smart home integration or full renovations. It’s more involved but gives a very clean finish.
Air Flow and Unit Placement Tips
I cannot stress this enough. Placement is everything.
The best position is usually high on a structural wall with a clear throw across the longest part of the room. You want the cooled air to travel over the main occupied area, not straight into a set of curtains or kitchen cabinets.
A few practical tips:
- Avoid mounting directly above ovens or cookers where rising heat can interfere with sensors
- Don’t position it where the airflow blows directly onto a dining table
- Keep it clear of beams and bulkheads that block air movement
- Ensure external pipe runs are practical and discreet
In a recent Lewisham installation, we adjusted the planned position by just over a metre to avoid a ceiling beam that would have disrupted airflow. Small changes like that make a big difference to comfort.
Zoning and Multi-Split Systems for Open-Plan Homes
Open-plan doesn’t always mean single temperature.
Some homeowners like the kitchen slightly cooler when cooking while keeping the lounge comfortable rather than cold. Zoning allows you to do that.
A multi-split system with separate controllers can give flexibility without installing multiple outdoor units. It’s a tidy solution and ideal when space outside is limited, which is common in parts of Epsom and Dartford.
If you’re already upgrading your heating system, for example pairing AC with underfloor heating downstairs, it’s worth designing both together so they complement rather than compete with each other.
Ceiling Fans vs. AC: Which Works Better?
This comes up in nearly every survey.
Ceiling fans don’t actually cool the air. They move it. That creates an evaporative cooling effect on your skin which makes you feel cooler.
In mild weather, a ceiling fan can be enough. But when indoor temperatures hit the high twenties, a fan just circulates warm air.
Air conditioning actively removes heat from the room. It also reduces humidity which makes a huge difference in kitchen areas.
In many cases, the best solution is both. AC to lower the temperature and manage humidity, ceiling fan on low speed to help distribute air gently without cold drafts.
Book an Air Conditioning Installation Survey
No two open-plan spaces are the same. That’s why a proper home survey matters.
During a visit we measure the room, look at glazing, check insulation levels and talk about how you use the space. Do you host big family gatherings? Is the oven on most evenings? Does the sun hit the bifolds from midday onwards?
We also consider external positioning for the outdoor unit, electrical supply and pipe routes. In some Kent properties we need to think carefully about neighbouring gardens and keeping noise levels sensible.
If you’re based in areas such as Dartford or Epsom, local knowledge helps. Different property styles bring different challenges.
Creating a cool open plan living space isn’t about the biggest unit available. It’s about the right capacity, correct positioning and thoughtful design so the whole room feels balanced.
If you’d like practical advice tailored to your home, the team at Henri-Taylor are always happy to help. You can get an Air Conditioning Quote and arrange a survey to see what would work best in your space.
A comfortable, usable living area all summer makes a real difference. And when it’s done properly, you’ll wonder how you ever managed without it.