With greener homes in today’s world comes a greater demand for energy-efficient products, increased insulation, and properly sealed building structures. Unfortunately, the benefits of greater efficiency come with unintended consequences… tighter houses that can lead to stale, unhealthy indoor air.
Residential Energy Recovery Ventilators
For Improved Air Quality & Better Health
A really airtight home creates a lack of air flow that involves all of those things that come into your house and from your house… like vapers or gases from cleaning agents, dust, pet dander, etc. Without a proper ventilation system to dilute it, it all gets trapped inside your home. Proper ventilation is the fix for refreshing breaths of fresh air.
Accordingly, also on demand the rising awareness about whole-house ventilation systems and the code requirements. Some of the most optimal are heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs), which require a bit more investment but are designed to reap greater efficiency in some climates.
How They Work
HRVs and ERVs offer an efficient approach to whole-house ventilation. Rather than simply exhausting or exchanging air, HRVs and ERVs transfer energy from the exhausting air to preheat or precool the incoming fresh air. Bringing the incoming air closer in temperature to that of the indoor air relieves some of the strain on the home’s cooling or heating system and reduces wasted energy.
As ERVs precondition outdoor air to near room conditions, fresh outdoor air flows through one side of the unit, while stale exhaust air from the home flows through the other side. An energy recovery wheel rotates between the two airstreams, transferring temperature and moisture properties. In Florida summers there is a significant reduction in the amount of energy used to condition the outdoor air when this transfer reduces the temperature and moisture level of the outdoor air.
The key difference between HRV and ERV systems is that energy recovery ventilators also transfer moisture in the air. If the air outside is more humid, the ERV will remove some of that moisture as it enters the home, and vice versa. For example, if the relative humidity outside is 80 percent and the interior humidity is 50 percent, the ERV will recover some of the humidity from the air entering the house, dropping it to about 65 percent, closer in line with the existing interior air.
According to the Energy Department, “Most energy recovery ventilation systems can recover about 70 percent to 80 percent of the energy in the exiting air and deliver that energy to the incoming air. However, they are most cost-effective in climates with extreme winters or summers and where fuel costs are high. In mild climates, the cost of the additional electricity consumed by the system fans may exceed the energy savings from not having to condition the supply air.”
When selecting an HRV or ERV, consult your HVAC contractor to ensure proper sizing for the home and to confirm that the unit is suitable for the climate. In extreme cold temperatures, for example, you may need a system with defrost functionality.
Improved cold-climate operation is one of the more recent advancements in HRV and ERV technology. Across the category, manufacturers continue to improve operations to boost efficiency while reducing the amount of power consumed. Slimmer units are now available for condos and smaller homes, and varied configurations of ports allow for installation flexibility in tighter spaces. Sizes to accommodate larger homes also are available.
And like so many other mechanical systems around the house, connectivity and control are key features. Homeowners can access and operate many ventilation components alongside the rest of the HVAC through a central control system at the home or from anywhere in the world via a smartphone.
The evolving technology is perfectly timed, as the popularity of whole-house ventilation is growing, manufacturers say, driven in part by increasing knowledge but also by new codes and standards.
In 2013 the requirements for the amount of fresh air that needs to be coming into homes has been increased. Awareness for HRVs and ERVs is stronger in places where the systems are specifically required; in other areas, it’s hit or miss among contractors who recognize the benefits and the importance of good ventilation.
In Minnesota, ERVs or HRVs are mandatory by code. In other states, it is not exactly a requirement for HRVs/ERVs, but a requirement for mechanical ventilation. This wasn’t true a few years ago because homes weren’t as airtight. As that changes and homes become more airtight, more codes require mechanical ventilation.
Even in areas where requirements don’t specify heat and energy recovery systems, the efficiency these units provide in some climates versus other methods is often worth the investment.
The Florida summers need humidity control more than anything, but improved indoor air quality is also a main concern. Breathing quality air leads to better health and increased comfort to building occupants, especially for those with as asthma or allergies. ERVs also reduce latent load on air conditioning equipment, reduce ventilation costs by as much as 75% producing year-round energy savings, and eliminate problems associated with high indoor moisture levels.
The ERV is designed for indoor and outdoor mounted applications requiring 500 to 12,000 cfm of ventilation air. A key design consideration for these units is mounting location. Several duct configurations allow for floor-mounted or ceiling-hung installation. Access panels and optional hinged doors allow for easy access to the unit’s wheel, filters, motors and controls.
The ERVe is designed for outdoor-mounted applications requiring 1,000 to 6,000 cfm of ventilation air. The configurability of this unit allows for easy incorporation on rooftops or outdoor pad-mounting scenarios. Hinged doors allow easy access to the unit’s wheel, filters, motors and controls.
The MiniVent is an energy recovery ventilator designed for indoor installations in commercial and industrial applications. Capacities range from 150 to 850 cfm and 1 in. wg of external static pressure. The compact design provides an economical solution for individual spaces, such as school classrooms and small offices and may be floor mounted or ceiling hung. A removable panel enables easy access to filters an enthalpy wheel.
The MiniCore is a total enthalpy core energy recovery ventilator for commercial and industrial applications. The compact design makes it ideal for applications where both sensible and latent energy transfer is necessary. Capacities range from 300 to 1,000 cfm and 1 in. wg of external static pressure. The MiniCore is designed for indoor installations with the option to be floor mounted or ceiling hung. Motor options include a standard PSC motor or a Vari-Green® motor for additional energy savings.
This diagram illustrates how energy recovery units can be used in conjunction with other HVAC equipment. Fresh, outdoor air enters the energy recovery unit and is pretreated before entering the heating and cooling equipment.
Energy recovery technology is well suited for commercial and institutional applications such as classrooms, offices, meeting rooms, condominiums and assisted living facilities, as well as residential single-family homes, condominiums, and townhouses.
Contact us today to discuss the best energy recovery ventilation system for your home.
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