Why Choosing the Right Size Matters
Investing in a ducted air conditioning system is a long-term decision that affects your comfort, energy bills, and overall heating and cooling efficiency. Yet, one of the most common mistakes property owners make is installing a system that is either too small or too large for their space.
An undersized system struggles to maintain the desired temperature, leading to excessive wear and tear. Meanwhile, an oversized system cools or heats too quickly, causing energy waste and inefficient operation.
Over the years, OneAir has provided expert advice to business owners and property developers looking for ducted air conditioning systems for their businesses or properties. This guide will help New Zealand business owners and property developers understand the key factors determining the right ducted system size, ensuring a good balance between performance, efficiency, and cost-effectiveness.
Factors to Consider When Sizing a Ducted System
1. The Size of Your Space
The most critical factor in selecting a ducted air conditioning system is the total floor area of your property. Here’s a general guideline for capacity requirements for rooms that are well-insulated with no large windows:
Floor Area (m²) | Approximate Cooling Capacity Needed (kW) |
50 – 80 m² | 5 – 7 kW |
80 – 120 m² | 7 – 10 kW |
120 – 180 m² | 10 – 15 kW |
180 – 250 m² | 15 – 20 kW |
250+ m² | 20+ kW |
Tip: Commercial spaces often require higher capacities due to higher occupancy levels, large glass areas allowing sun to enter, electronic equipment, and lighting generating additional heat.
2. Number of Rooms and Zoning Needs
Modern ducted systems can be fitted with zoning capabilities, allowing users to independently control airflow to different areas. This helps optimise energy use and customise comfort levels across various rooms.
Benefits of zoning include:
Lower energy consumption by cooling or heating only occupied spaces
Improved comfort by setting different temperatures for different zones
Extended lifespan of the HVAC system due to reduced workload
Choosing a ducted system with zoning functionality significantly improves efficiency if your property has multiple offices or residential rooms with varying occupancy rates.
3. Insulation Levels of the Property
The better your property’s insulation, the less energy your ducted system will need to maintain indoor temperatures. Proper insulation reduces the size requirements for your system by minimizing heat loss in winter and preventing excessive heat gain in summer.
What to check:
Ceiling and wall insulation levels
Double-glazed windows for heat retention
Air leaks around doors and windows
Pro Tip: A well-insulated property can reduce heating and cooling costs by 20% or more.
4. Energy Efficiency and Running Costs
Choosing an energy-efficient ducted system lowers your electricity bills and reduces your carbon footprint.
Key features to look for:
Energy Star Rating: Higher star ratings mean better efficiency
High efficiency (EER) : Higher EER numbers mean the system is able to convert each unit of electricity into more cooling performance
Inverter Technology: Adjusts compressor speed based on demand, saving energy
Cost Analysis:
Pro Tip: While an energy-efficient system might have a higher initial cost, it typically pays for itself within a few years for commercial applications through lower electricity bills.
Common Mistakes When Choosing a Ducted System Size
Going Too Small
Causes the system to run continuously, increasing noise as well as wear and tear levels
Struggles to maintain temperature, leading to occupant discomfort
Going Too Big
Higher up-front cost
Short running cycles lead to inefficient operation and on/off wear and tear
Inconsistent temperatures regulation
Ignoring Zoning
Wastes energy by cooling or heating unused areas
Overlooking Professional Advice
Relying on guesswork instead of an HVAC specialist’s recommendations can lead to poor system design and performance
Benefits of a Properly-Sized Ducted Air Conditioning System
Lower Noise and Energy Bills: An optimally sized system ensures it is working at medium-low speed. This allows the system to run quietly as well as, reducing electricity costs.
Consistent Comfort: Maintains a stable indoor temperature without large fluctuations.
Longer Equipment Lifespan: Prevents overworking, reducing the risk of premature breakdowns.
Better Air Quality: Proper sizing and system design will complement fresh air distribution and improve indoor air quality by drawing air into well-placed return grilles, thus enhancing air circulation. This is especially crucial for commercial spaces where higher occupancy levels mean air quality is even more critical for the health and work performance of staff.
How to Get the Right System for Your Property
The best way to determine the correct size for your ducted air conditioning system is to consult a professional HVAC specialist. They will:
Conduct a property assessment
Assess sun strike, insulation, zoning, and climate
Design a system with correct ducting and grille sizes
Recommend the best type and most efficient system for the available budget
The Right Size Ducted Air Conditioning System = Comfort & Savings
Choosing the correct size ducted system for your home or business is not just about square footage — it involves sun angles. Window size and positioning, insulation, zoning, energy efficiency, and climate factors. A well-sized system ensures minimum sound levels, lower operational costs, greater comfort, and a longer-lasting investment.
For expert advice on selecting the perfect ducted air conditioning system, contact our team today for a free consultation.