Fire Station HVAC 101: Making the Right Choice for Your Station

When selecting the optimal heating, ventilation, and air conditioning (HVAC) system for your fire station, it is essential to evaluate both conventional options and emerging technologies to ensure an informed decision is made in today's evolving market.

Traditional systems offer advantages such as cost-effectiveness, established reliability, and consistent air distribution. However, they may also present disadvantages, including inefficient energy use, high maintenance expenses, and limited control capabilities.

It is key to acknowledge that an HVAC system’s success hinges on its ability to maintain indoor comfort levels, regardless of outdoor conditions. These systems also seek to maintain a balance between dry bulb temperature (the temperature you feel or sense), versus relative humidity, which is the ratio of the amount of water vapor present in the air to the greatest amount possible at the same temperature. This balance is known as the “comfort zone.”

Choosing the right HVAC system isn’t just about cost savings — it’s fundamental to ensuring comfort, supporting job performance, and maintaining safety. Tools like the psychrometric chart can help determine which system best supports your comfort zone for your specific location. Still, your ultimate choice should also consider factors such as budget, functionality, user-friendliness, and potentially your openness to exploring innovative solutions.

Comfort zone

One important consideration to make when selecting a new HVAC system is its ability to maintain a stable indoor temperature. A well-balanced temperature in the workplace has been linked to increased productivity levels, as a University of Chicago study found that productivity can drop by as much as four percent per degree when temperatures rise above 80 degrees. 

Furthermore, comfort zones also consider relative humidity (RH), which is ideally maintained within a range of 48 to 60 percent. RH levels are subject to seasonal variation and may decline to approximately 25 percent during winter in certain regions due to drier air conditions. Implementing an HVAC system capable of consistently regulating both temperature and indoor RH is essential for ensuring optimal job performance and promoting occupant well-being.

It is crucial to prioritize occupant comfort within the living and administrative spaces of a firehouse, which are often referred to as “cold spaces, or green zones”. Maintaining consistent, comfortable temperatures offers first responders an environment in which they can adequately recover and rehabilitate — serving as a cool respite following summer emergencies or providing warmth and dryness during winter operations.

Pros of traditional systems

There are a variety of positives that come with traditional HVAC systems. A constant air volume (CAV) rooftop unit is a straightforward, low-maintenance solution that stays unobtrusive on the roof. It provides consistent, even air distribution, which creates trusted comfortability. A CAV system also provides effective dehumidification, heating, ventilation, and cooling, all in one unit package.

A heat pump split system combined with a dedicated outdoor air system (DOAS) offers multiple thermostats, enabling precise control of individual spaces. This arrangement enhances energy efficiency and minimizes unnecessary energy consumption. This system offers both heating and cooling capabilities year-round. It operates with low costs and utilizes minimal to no fossil fuels, making it environmentally sustainable, and features an extended service life exceeding 20 years.   

Traditional boiler plant systems operate by heating water and circulating it throughout the building to provide warmth where needed. This type of system doesn’t necessarily require unsightly and expensive ductwork, is highly durable and dependable, creates better zoning and controllability, and provides effective and consistent heating, as water tends to hold heat better than air.

For strictly cooling, an evaporative “swamp” cooling system comes with low installation costs, uses much less energy than some other options, and is environmentally friendly as it does not utilize refrigerants.

Cons of traditional systems

CAV rooftop units have constant airflow to all spaces, which can lead to an abundance of energy wastage, while constant airflow can restrict comfort control or flexibility. By nature, rooftop units also have a greater potential for roof leaks, produce higher noise levels, and can be visually unappealing.

A heat pump split system equipped with DOAS typically involves higher installation expenses, presents maintenance challenges, and has historically operated with reduced efficiency under low temperature conditions. Furthermore, the entire heat pump system is limited to functioning in either heating or cooling mode at any given time.

Traditional boiler plant systems typically incur elevated installation expenses because of intricate setup and maintenance requirements, they lack integrated cooling functions and typically rely on fossil fuels for operation. Additionally, these systems require substantial space for construction and present a risk of leaks.

Evaporative cooling systems have limited cooling capacity and rely on the evaporation effect. For larger spaces with higher occupant numbers, it may be difficult for an evaporative cooling system to maintain comfort levels. In addition to this, evaporative cooling systems require frequent cleaning to avoid bacteria growth and are ineffective in more humid climates.

Additional variables

Factors like call volume, bay door usage, and temperature recovery time all affect a system’s return on investment (ROI) and efficiency and should be considered when choosing the best option for a station. As a quick example, a busy station in northern America will experience constant cycles where the bay doors are opened, and the heat in the bays is lost. Understanding these cycles is crucial when designing the HVAC system so recovery time is reduced, while also trying to be as efficient as possible. 

Geographic location is an important factor influencing indoor temperatures and must be taken into account, along with the intended functions and specific areas within the facility. Variations in state regulations and mandated energy efficiency standards will result in differing building envelop designs, which, in turn, will also impact system requirements.

The type of utility in use depends on the region and can influence ROI. For instance, in the northeast, gas-fired packaged CAV rooftop units, cooling-only rooftop units, and heat pump split systems with DOAS are more commonly used traditional systems compared to other regions.

New age solution

A variable refrigerant flow (VRF) Heat Recovery System is an HVAC system that can simultaneously provide both heating and cooling to different zones of a building. These innovative systems offer the same benefits as a heat pump system, but with better temperature and humidity control. VRF Heat Recovery System’s also provide higher energy savings than a traditional heat pump and provide better efficiency.  

Although VRF Heat Recovery System installation expenses are greater when compared to conventional systems, these costs may be reduced when the system is integrated with other systems. This method was ultimately chosen by the Massapequa Fire District for their Park House on Long Island, NY (represented in several of the images). The District was looking for a system that focused on aesthetics, comfort, and the area’s limited space constraints. Ultimately, a hybrid system was selected, with the VRF system designated for all cold/green zone areas and CAV rooftop units assigned to serve the larger spaces on the second floor.

After building commissioning was completed, this hybrid model functioned well for the client. The average measured space temperature was 70 degrees, and the RH came in at 51 percent, right in line with the Fire District’s desired comfort zone.

Conclusion

Selecting the most appropriate HVAC system for a fire station may appear challenging, given the wide range of available options, varying price points, and the necessity to consider geographic location and other essential factors.

Regardless of what avenue you choose, the end goal should always be the comfort and safety of first responders. While factors like climate, geography, and system type are critical in the decision-making process, they ultimately serve a greater mission: supporting those who serve others in the community.

Whether opting for a traditional system, a new-age solution, or a hybrid of the two, fire stations must prioritize systems that ensure clean air, consistent temperatures, and reliable performance. The comfort and well-being of first responders isn’t just a luxury, but a necessity.