A sustainable, earth-friendly mindset requires us to make use of everything we can in an efficient manner. Sometimes, we can even make use of something we would rather not have. Take condensation for example. What happens when the condensation that forms after humid air cools settles inside HVAC equipment?  We wind up with rust and corrosion that raises HVAC maintenance costs and compromises equipment life. Nasty stuff, yes? But what if the condensation is used to our advantage?

The idea begins with a desire to maximize the transfer of latent heat—a quality of Energy Recovery Ventilators (ERVs) that separates them from Heat Recovery Ventilators (HRVs), which only transfer sensible heat. An effective ERV offers precise control of moisture coming from the air without dropping the temperature in the process. How do we control that moisture best, thus maximizing latent efficiency?

Let us first examine the difference between sensible and latent heat.

Sensible Heat Versus Latent Heat.

Sensible heat is what you measure with a standard thermometer. It is the heat contained in the air itself. This type of energy might change the temperature of an object, but it won’t change it from one state to another. It is heat you can feel or sense.

Latent heat, however, will cause a change in state such as water becoming water vapor and resulting in condensation. A wet-bulb thermometer is used to measure the constant temperature of latent heat. Such energy is instrumental in Latent Only Cooling, which is used to control moisture.

Sensible Cooling Versus Latent Cooling.

When we run HVAC to lower the temperature of a room, the system’s sensible cooling capacity increases its ability to remove heat.

Latent only cooling is a method of utilizing the cooling energy of air leaving an existing or new construction fan coil or air handler to simultaneously pre-cool the air entering the air handler and reheat the air leaving the cooling coil. Installations and field tests have shown this can take an average fan coil (either direct exchange (dx) or chilled water type) and render the unit up to over 95% latent with very little temperature change. How well a system such as an ERV does this is measured by latent efficiency as compared to climate conditions. As mentioned earlier, the most effective ERV can offer precise control of the moisture in the air without dropping the temperature in the process.

BPE, Inc. Regenerative Condensate Return® Technology for Latent Efficiency

Using a sustainable mindset, we can make use of the condensation created by cooling hot and humid fresh air within a few degrees of room temperature to better an HVAC system rather than compromise it. Building Performance Equipment, Inc. has patented the technology for utilizing excess condensation by transferring it into the exhaust stream rather than into your building. In doing so, it provides improved heat transfer while avoiding the need to drain the condensate. Basically, BPE Regenerative Condensate® Return Technology recycles moisture to increase thermal effectiveness, making BPE ERVs over 90% sensible with 34% latent effectiveness, as tested by Edison Testing Laboratory. 

With a plethora of ways for today’s buildings—new or retrofitted—to reuse, recycle, and repurpose, it only makes sense to involve such sustainable thinking in HVAC design. When an ERV can use the energy from air on its way out of a structure as well as the condensation we want to get rid of in the first place to create comfort, healthy IAQ, and low energy bills, what is there to lose by employing sustainable HVAC?

BPE, Inc. ERVs fit easily into the simplest to most complex structures. They are modular up to 20,000 cfm and—thanks to transfer of condensation—they are easily maintained. Contact Haglid Engineering to discuss how we can implement a BPE ERV into your unique HVAC needs.

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