ASAC News & Updates

Why Size Matters

Sat, 14 Mar 2026 10:02:17 GMT

Choosing the right air conditioning system isn’t just about buying the most powerful unit available. In fact, oversizing or undersizing an air conditioner can reduce efficiency, increase energy costs, and make your home less comfortable .

Professional HVAC engineers determine the correct unit size using a cooling capacity measurement known as BTU (British Thermal Units) . Understanding how this works — and what influences the calculation — helps homeowners make better decisions when installing air conditioning.

What Does BTU Mean in Air Conditioning?

Air conditioning capacity is typically measured in BTUs per hour (BTU/h) . This represents how much heat the unit can remove from a room within one hour.

As a general guide:

Room Size Typical Cooling Requirement

Small bedroom (10–15 m²) 5,000–7,000 BTU

Medium room (15–25 m²) 8,000–10,000 BTU

Large room (25–40 m²) 12,000–14,000 BTU

However, room size alone does not determine the correct air conditioning capacity . Many other factors influence how much cooling power is needed.

Key Factors That Affect Air Conditioning Size

1. Room Size and Ceiling Height

The first step in calculating cooling requirements is determining the volume of the space . A room with high ceilings holds more air than a standard-height room, meaning the air conditioner must remove more heat to maintain a comfortable temperature.

For example:

A large open-plan living area may require significantly more cooling than a smaller enclosed room.
Loft conversions and converted barns often require larger systems due to higher ceilings.

2. Sun Exposure

Rooms that receive strong sunlight during the day naturally accumulate more heat. South-facing rooms or spaces with large glass windows may require 10–20% more cooling capacity than shaded rooms.

Examples include:

Conservatories
Garden rooms
Rooms with floor-to-ceiling glazing

3. Number of Occupants

People generate heat. A typical adult produces around 400–600 BTU of heat per hour .

In busy spaces such as:

Living rooms
Home offices
Meeting rooms

…the cooling load increases with the number of occupants.

4. Heat-Producing Appliances

Electronics and appliances also contribute heat to a room.

Examples include:

Computers and gaming equipment
TVs
Kitchen appliances
Lighting systems

A home office filled with equipment will require more cooling power than a simple bedroom.

5. Insulation and Building Materials

Well-insulated homes retain cool air more effectively. Poor insulation, older windows, and draughty construction allow heat to enter the space faster.

Key influences include:

Roof insulation
Wall insulation
Window glazing
Sealing of doors and ducts

Improving insulation can reduce the size of air conditioning unit required and lower energy costs .

6. Room Type

Different spaces have different cooling demands.

For example:

Bedroom - Lower equipment heat load
Kitchen - High heat from appliances
Home Office - Extra heat from electronics
Conservatory - High solar heat gain

Each of these factors contributes to the final cooling requirement.

Why Getting the Right Size Matters

Choosing the correct air conditioning capacity is important for both comfort and efficiency.

Undersized units

Struggle to cool the room
Run constantly
Increase electricity costs

Oversized units

Cool the room too quickly
Switch on and off frequently
Fail to properly remove humidity

Professional HVAC engineers perform detailed load calculations to ensure systems are correctly sized.

Quickly Estimate Your Cooling Requirements

If you'd like a quick estimate for your room, you can use our interactive air conditioning calculator here:

https://www.asac.uk/quick-AC-calculator#QuickCalculator

The calculator considers factors such as:

Room size
Ceiling height
Sun exposure
Number of occupants
Equipment heat load

This gives you a fast indication of the BTU capacity you may need , along with suggested air conditioning units suited to your space.

When to Get a Professional Survey

Online calculators are a great starting point, but for permanent installations — especially for larger homes, offices, or commercial properties — a professional survey ensures the system is designed correctly.

At ASAC , our engineers assess:

Building insulation
Heat gain
System positioning
Airflow requirements

This ensures you receive a system that is efficient, reliable, and perfectly matched to your property .

Get Expert Advice

If you're considering installing air conditioning, the best first step is a no-obligation assessment of your requirements .

Use our quick calculator to get started:
https://www.asac.uk/quick-AC-calculator#QuickCalculator

Or contact the ASAC team to arrange a professional survey and tailored recommendations for your home or business.

Optimising Thermostat Settings and Improving Household Efficiency

Fri, 06 Mar 2026 14:37:07 GMT

Your thermostat plays a key role in maintaining comfort while managing energy consumption. By optimising your thermostat settings and adopting a few simple efficiency habits, you can significantly improve how effectively your air conditioning system operates.

Small adjustments can lead to noticeable savings without sacrificing comfort.

Choosing the Right Temperature

Setting your thermostat too low can cause your system to work harder than necessary, increasing energy use and putting extra strain on equipment.

During warmer months, many experts recommend setting the thermostat around 24–26°C for cooling. This range generally provides a comfortable indoor environment while maintaining good energy efficiency.

For heating in colder months, a setting between 18–21°C is typically sufficient for most homes.

Using Programmable or Smart Thermostats

Programmable and smart thermostats can automatically adjust temperatures throughout the day based on your schedule.

For example, temperatures can be slightly higher while you are away from home and return to a comfortable level before you arrive. This avoids unnecessary cooling or heating when rooms are unoccupied.

Smart systems can also learn household routines and allow remote control via mobile apps.

Improving Overall Household Efficiency

Thermostat optimisation works best when combined with other simple efficiency measures:

Close blinds or curtains during hot weather
Reducing direct sunlight helps keep indoor spaces cooler.

Use ceiling fans where possible
Fans improve air circulation, allowing you to feel comfortable at slightly higher temperatures.

Keep air filters clean
Clogged filters restrict airflow and force systems to work harder.

Avoid heat-generating appliances during peak heat
Ovens, dryers and other appliances can increase indoor temperatures during hot periods.

Consistency Is Key

Constantly adjusting the thermostat can actually reduce efficiency. Maintaining a consistent temperature helps your system operate more effectively and reduces unnecessary cycling.

Getting the Most From Your System

Regular servicing ensures your air conditioning system continues to perform efficiently. A well-maintained system responds better to thermostat settings, uses less energy and provides more reliable comfort.

With the right settings and a few simple efficiency habits, homeowners can enjoy a comfortable indoor environment while keeping energy use under control.

Preventing Energy Loss: Sealing Gaps and Insulating Ducts

Sat, 07 Feb 2026 13:57:40 GMT

Many businesses and homeowners are surprised to learn how much energy is lost through small gaps and poorly insulated ductwork. Even a well-designed air conditioning system can struggle to perform efficiently if cool air escapes before reaching the rooms where it’s needed. Sealing gaps and properly insulating ducts are two simple but highly effective ways to improve your home’s comfort while reducing energy costs.

Why Energy Loss Happens

In many homes, air can escape through small cracks around windows, doors, loft spaces and service openings. These gaps allow cooled air to leak out while warm air enters, forcing your air conditioning system to work harder to maintain a comfortable temperature.

Ductwork can also be a major source of energy loss. If ducts run through uninsulated loft spaces or garages, the cool air travelling through them can quickly warm up before it reaches your living areas. Over time, this means your system must run longer and use more electricity to achieve the same level of comfort.

Sealing Gaps Around the Home

One of the easiest ways to improve efficiency is to identify and seal common air leaks. Areas worth checking include:

Window and door frames
Loft hatches
Pipe and cable entry points
Skirting boards and floor gaps
Around extractor fans and vents

Simple solutions such as weather stripping, sealant or draft excluders can significantly reduce unwanted airflow.

Insulating Ductwork

Duct insulation helps maintain the temperature of air as it travels through the system. Without insulation, ducts in warmer areas of the home can cause cooled air to warm up before it reaches its destination.

Proper insulation:

Reduces energy loss
Improves system efficiency
Helps maintain consistent temperatures
Reduces strain on your air conditioning system

Professional inspections can also identify loose connections or leaks in ductwork that may be contributing to energy waste.

Long-Term Benefits

By sealing gaps and improving insulation, homeowners can enjoy:

Lower energy bills
Improved indoor comfort
More efficient system performance
Reduced wear on equipment

Small improvements in energy efficiency can make a noticeable difference to both comfort and running costs.

If you’re unsure whether your air conditioning system is operating efficiently, a professional assessment can help identify opportunities to improve performance. Book in a Servicing Appointment TODAY.