Choosing the right HVAC for a commercial building is more than just finding something that works. It’s about finding something that’s custom to the building. Size, air quality, climate, space all come into play. Upfront costs matter of course but it’s the long term savings and efficiency that really count.
Every commercial space is unique and so should its HVAC. For example a large shopping centre will need a different system than a small office building. The goal is to find a system that matches your building’s needs and maximises energy efficiency. Higher efficiency systems may cost more to install but will save a lot in energy costs down the line and improve indoor air quality.
Building Size and Square Footage
HVAC systems are measured in tons, most commercial systems fall between 2 and 30 tons. One ton of HVAC capacity can remove around 12,000 BTUs (British Thermal Units) of heat per hour. To figure out how much cooling your building needs you’ll first need to calculate its cooling load.
Here’s a quick way to estimate that:
- Multiply your building’s square footage by 12,000, then divide by 500.
- Add 380 BTUs for each occupant.
- Add 1,200 BTUs for each kitchen.
- Add 1,000 BTUs for each window to account for solar radiation.
- Divide the total by 12,000 to convert it to tons.
This will give you a good idea of the size HVAC system you’ll need to cool your space.
HVAC Sizing and System Selection
There’s a rough rule of thumb that says one ton of cooling is needed for every 350 to 400 square feet. But getting your heat gain and heat loss calculations right is more important than just following a rule of thumb. Heat gain happens when the sun or internal sources like people and equipment warm the building, while heat loss occurs when the building’s insulation and windows let warmth escape. These calculations are important when choosing the right HVAC system to maintain comfort and efficiency for your building.
Once you have a clear understanding of your building’s heating and cooling needs you can select the system that best fits. Here’s a breakdown of the most common types of HVAC systems:
- Packaged Systems: All-in-one units that combine the compressor, condenser, evaporator and fan coil in one package. Great for buildings with limited space like hotels, hospitals and other commercial spaces. Some packaged systems are called PTACs and are mounted in windows and can do both heating and cooling.
- Split Systems: Like the units you’d find in residential buildings, split systems are used in smaller commercial spaces like offices or restaurants. They connect to the building’s ductwork and can be controlled by thermostats. But you may need separate units for different areas that require their own temperature control which can increase upfront costs and maintenance.
- Rooftop Units (RTUs): Compact units mounted on the roof, saving space inside the building. RTUs are easy to install and can do both heating and cooling while circulating air through ducts to keep the interior comfortable.
- Variable Refrigerant Flow (VRF) Systems: More advanced and energy efficient. VRFs don’t need ductwork, making them a quieter and more flexible option for larger buildings. They use heat pumps or heat recovery systems to move refrigerant between a central unit and indoor zones to keep temperatures consistent.
Oversized vs. Undersized Systems
Bigger isn’t always better with HVAC systems. An oversized system will cool the space too quickly and lead to poor humidity control and discomfort. It will also waste energy, increase utility costs, cause more wear and tear and require more maintenance.
On the other hand an undersized system will struggle to meet your building’s needs. It will run constantly to keep up with the demand which puts more strain on the equipment and leads to higher energy costs and shorter lifespan of the system.
Commercial HVAC Systems for Different Building Sizes
Here’s a breakdown of commercial HVAC systems by building size:
- Small Buildings: Split systems or packaged terminal air conditioners (PTACs) work well for smaller spaces like offices and restaurants. They’re easy to install and provide efficient cooling but zoning can make things more complicated and expensive.
- Medium to Large Buildings: VRF systems or rooftop units (RTUs) are better suited for buildings with multiple zones or larger spaces. These systems offer customized temperature control and are more energy efficient than traditional units.
- Large Buildings: For larger buildings especially in colder climates chillers and boilers are a good option. These systems are more efficient than rooftop units and can do both cooling and heating which reduces energy usage.
Ductwork and Airflow Design Considerations
Ductwork design becomes even more important in larger buildings. Proper ventilation and airflow helps maintain a comfortable indoor environment especially when windows aren’t an option for fresh air. Commercial buildings need a more organized approach to managing airflow.
Here’s what to consider when designing ductwork:
- Sizing and Layout: The ducts should be sized properly to ensure consistent airflow throughout the building. Think about room sizes, ceiling heights and equipment capacities to make sure everything is balanced.
- Airflow Distribution: Use diffusers, registers and adjustable dampers to distribute air evenly. This prevents some areas from being over-conditioned or under-conditioned.
- Pressure Balancing: Maintain the right pressure levels by ensuring the fan capacity is appropriate and duct joints are sealed well. This will minimize energy loss and keep the airflow consistent.
Good ductwork design not only keeps the building comfortable but also maximizes energy efficiency and indoor air quality.
Energy Efficiency and Control Systems
Energy efficient HVAC systems use advanced controls to reduce energy usage while keeping the indoor environment comfortable. Zoning, programmable thermostats and building automation systems (BAS) all contribute to better energy management.
Here’s how these control systems work:
- Zoning: Dividing a building into zones allows you to control the temperature in each area. This saves energy in rooms that aren’t being used.
- Programmable Thermostats: These thermostats allow you to set temperatures for different times of the day so you don’t waste energy when the building is empty.
- Building Automation Systems (BAS): BAS integrates all the building systems like HVAC, lighting and security into one platform. This makes it easier to coordinate everything and optimize energy management.
Energy efficient HVAC systems use these controls to keep the building comfortable while keeping utility bills low.
Installation Logistics and Project Management
Installing or upgrading an HVAC system in a commercial building is a complex process. Hire a contractor with experience in large projects. An experienced contractor will help you manage your budget, timeline and the selection of the right equipment.Planning is key to minimizing downtime during the installation.
A good contractor will break the process into phases to minimize the impact on your business and help you stay within budget.
Code Compliance and Permits
Your contractor should be familiar with all the permits and regulations. They will ensure the installation meets local, state and federal codes and can help expedite the permitting process so your project stays on schedule.
Contact Unitemp Today!
Choosing the right HVAC system for your commercial building is a big decision that affects comfort, efficiency and long term costs. By understanding your building’s needs and selecting the right system you’ll be able to ensure your HVAC installation is a success.
Thinking of upgrading your HVAC system? Call Unitemp. With over 50 years of experience working with commercial clients in New Jersey and New York we specialize in energy efficient solutions for your business. 877.704.4822 for a full evaluation and to find out how we can help with your HVAC system.