Air handling unit cost: what is the return on investment?

The US Environmental Protection Agency (EPA) has reported that indoor air pollution is among the top five environmental health risks. With most of us spending the majority of time at home, especially in the wake of a global pandemic, the need to ensure good air quality at home is urgent. An air handling unit (AHU) is dedicated to removing polluted air from indoor spaces and replacing it with clean, fresh and healthier air.

The general public is becoming more aware of pollution levels and the negative health effects that can be the result of pollution and particulate matter (PM) present in poor quality indoor air. The need to address this and provide a cost-effective, efficient solution is becoming increasingly important.

Due to these issues, there's a vital need to consider a number of factors when installing an AHU. These include cost, energy consumption, efficiency, and noise level. 

How to choose the right system for your activity

When deciding which air handler is right for you, it’s important to consider aspects such as energy consumption and noise level, as well as the more technical side of air handling units. 

We recommend choosing a unit with a Eurovent Certified performance, so you have an accurate representation of the important aspects of an AHU.

Here are some other points to look out for when choosing an air handler:

• To ensure your system is energy efficient, choose an AHU with a face velocity of no more than 1.5 m/s. 
• Also with energy efficiency in mind, make sure the pressure drop over the AHU is no greater than 250 Pa.
• Eurovent’s energy efficiency classification system rates for performance and mechanical characteristics. The system runs from A+ (the most efficient) to E. It is recommended to choose a class A unit.
• Use a life-cycle cost analysis to assess the size of AHU that you require.
• Measures to reduce noise disturbance caused by fans can increase pressure drop across the system. Avoid the need for such measures by checking sound power levels across all octave bands, not just the averaged.
• 250Hz is generally the most difficult active band to dampen. When choosing between  two fans of equivalent energy performance, select the one with the lowest sound power level in the 250Hz band.
• Prevent sick building syndrome (SBS) by avoiding uncontrolled condensation in AHUs.
• Design your outdoor air intakes so they prevent rain and snow from entering and becoming trapped inside. 
• Keep birds out of intakes and discharges by fitting them with wire mesh screens.

What is the return on investment?

When considering the cost of an AHU, it’s vital to not only consider the unit price, but also the total cost of maintaining and running the unit. Energy efficiency is one of the most relevant considerations when assessing whether a product is suitable for your application. 

Air handling processes can include a number of different treatment processes such as fans, heating and cooling, humidification, dehumidification, and filtration. All of these processes consume energy, which can be costly. 

Annual consumption

The annual consumption of energy required by an AHU is usually very high. It's affected by factors such as indoor climate conditions, ambient climate, system design, and how it is operated. The amount of power used to treat the ventilation air increases the enthalpy change (heat absolved or evolved) and the airflow rate. The energy used by the fans to distribute the air increases with the airflow, pressure and efficiency of the fan and its drive system. The total annual energy consumption is derived from the sum of these processes.

Since building energy is accountable for 40% of Europe’s energy usage and HVAC plant energy is the largest component of that, it’s essential to properly investigate how to efficiently operate a ventilation system and consider that alongside the unit’s cost.

For most companies, the financial aspect is usually the most important factor in considering choices. Being able to see the whole picture, instead of zoning in on details, should be the main focus. This requires economic analysis in system, technology, and equipment selection, as well as an investigation that evaluates all costs during the lifetime of the ventilation system through a Life Cycle Cost (LLC) analysis.

Life Cycle Cost (LLC) analysis

An LCC assessment is a prediction that allows different solutions to be compared, using certain assumptions and historical climate data. It can be a useful tool in guiding your decision on what AHU is the best choice for you. 

An LCC assessment commonly comprises the cost of acquisition (investment, installation and commissioning), energy costs for running the AHU, and all other associated costs. 
Some costs are incurred at the outset, such as unit cost and installation, however others, such as part replacement and maintenance, may occur during the lifespan of the system.

It is essential to consider all of these factors in your decision-making.  

Considering the energy expenditure is vitally important, as this can account for as much as 80% of the total costs. It is worth considering the investment cost of an AHU with an optimised energy recovery system against an initially lower-priced, but less efficient unit.

Another important issue to consider is the possible impact of each AHU on associated aspects of the system, such as other HVAC components. Many functions in the unit are related to other components. For example, energy recovery is related to boiler capacity and water chiller performance and the associated distribution systems. 

Therefore, a more expensive unit with a better energy recovery performance will reduce the investment for thermal energy supply, while a more costly, larger unit with highly efficient fans might decrease the investment for electric power supply.  All these investment interactions must be considered in the LCC calculation.