How we estimate air conditioning running costs

Understanding our running cost estimates

At BOXT, we want to give you an accurate picture of what it costs to run your new air conditioning unit. Because every home is different, we use a standardised "Baseline Room" model to ensure our estimates are fair, consistent, and based on real-world UK data.

1. Room sizing

To calculate how much energy is needed to cool or heat your space, we look at four typical room sizes:

• Small (12m²): e.g., A home office or nursery.

• Medium (23m²): e.g., A standard double bedroom.

• Large (35m²): e.g., A spacious living room.

• Extra Large (50m²): e.g., An open-plan kitchen and dining area.

2. Our calculation methodology

We break your costs down into two distinct phases:

A. The startup phase (The initial push)

When you first turn your AC on, it works at its maximum power to reach your desired temperature quickly.

• Cooling: We calculate the energy needed to drop the room temperature by 7°C (e.g., from 29°C down to 22°C).

• Heating: We calculate the energy needed to raise the temperature by 8°C (e.g., from 16°C up to 24°C).

B. The maintenance phase (More efficient running)

Once your room reaches the right temperature, the smart "Inverter" technology in your unit slows down. It then uses only a small amount of power to maintain that comfort level, offsetting the natural heat loss of your home.

3. Where do the numbers come from?

Our estimates incorporate three key industry benchmarks:

• UK insulation standards: We assume your home meets "Average UK Standards" (Double glazing, wall insulation, and loft insulation) as defined by UK Building Regulations (Part L).

• Occupancy heat: Humans naturally give off heat. Our estimates account for adults resting in the room, using data from the CIBSE (Chartered Institution of Building Services Engineers).

• Real energy prices: We update our costs based on the latest Ofgem Price Cap.

The fine print

These figures are for illustrative purposes to help you compare your options. Your actual costs may vary depending on how much you pay for your electricity, how many windows you have, which direction the room faces (south-facing rooms get more sun), and your specific insulation levels.

Quick Reference Table