Unico System Provides Better Efficiency & Humidity Control in Newer, Tighter Homes Than Higher-Rated

SEER HVAC SystemStudies conducted by the Florida Solar Energy Center (FSEC), a research institute of the University of Central Florida, indicate significant energy usage reductions achieved by Unico air handling units when compared to traditional air conditioning units with much higher SEER ratings. FSEC’s tests also documented a greater reduction in average daily relative humidity levels by The Unico System, resulting in even greater energy savings.

The Search for an Integrated Solution to Humidity Removal with Energy Efficient HVAC

These studies, conducted from 2015 through 2017 at FSEC’s Manufactured Housing Laboratory, were part of a larger effort to determine optimal humidity solutions for low-load homes. The problem is that while modern building technologies have made homes much tighter, reducing the energy needed to sufficiently cool them, the activities within homes that generate heat and moisture still have an impact on the cooling load and need to be dealt with – preferably in an efficient way.

The cooling load “is the amount of heat energy that needs to be removed from a space to maintain the temperature in an acceptable range.” To determine the right size for an air conditioning system, installers first perform calculations to determine the home’s cooling load. The heat energy to be removed falls into two categories: the sensible load and the latent load.

The sensible load factors in outside heat that infiltrates through ceilings, walls, windows and floors. Think of sunlight streaming through windows and warming a room, or a sweltering attic caused by the sun shining on a roof throughout a hot summer day. The latent load, on the other hand, deals with interior heat and moisture generated by people and appliances. Examples include lighting, stoves, ranges, refrigerators, TVs and computers, ventilation (bringing in outside air), showering and even perspiring.

While building technologies have done a lot to reduce the sensible load (hence the term “low-load” homes), they do nothing to offset the latent load. The amount of heat and humidity we generate while we go about our daily activities has an impact on our home’s interior environment. This additional heat and moisture needs to be removed for us to feel comfortable.

In the past, the most common solution to this problem has been to either overcool the space, or add supplemental dehumidifying systems, or a combination of both. Overcooling results in cold, clammy discomfort; is unreliable in shoulder seasons (spring and fall); and is energy wasteful: your air conditioner is working either harder or more often than it needs to (or both). Supplemental dehumidifiers add heat back into the conditioned space (which then has to be removed by the A/C system) and consume additional electrical energy.

Variable capacity heat pumps – systems that can vary compressor speed, refrigerant flow rate, and air flow, enabling an output range from 10-120% of nominal rated capacity – would appear to provide a better solution to this dilemma. However, previous FSEC tests conducted from 2010 through 2015 on conventional variable capacity heat systems indicated very little impact on relative humidity levels, and these systems were not able to consistently perform at their stated lowest energy consumption capacities.

However, later studies indicated that the small-duct high velocity Unico System air handler paired with its iSeries outdoor inverter unit demonstrated marked energy efficiency while significantly reducing relative humidity levels in a head-to-head comparison with a conventional high SEER variable capacity condensing unit and air handler.

Fig. 1: Sensible & Latent Loads1

Unico Air Handler & iSeries Inverter Combine to Efficiently Reduce Relative Humidity

At the Florida Solar Energy Center, in a head-to-head comparison between a Unico System iSeries outdoor inverter unit with a 14 SEER rating and a conventional variable capacity heat pump with a 22 SEER rating, the Unico air handling unit consistently consumed less electrical energy while significantly reducing the relative humidity in the FSEC 16,000 sf low-load Manufactured Housing Laboratory.

The lower fan efficiency of the Unico air handling unit is greatly offset by its daily energy usage, which is 22% lower than that of the 22 SEER system. This is due to The Unico System’s ability to operate on stand-by power 68% lower than the 22 SEER system, and to maintain comfortable temperature and relative humidity levels at 45% of its maximum airflow capacity. The Unico System also meets the required load by providing a supply air temperature 9° F colder than the conventional system.

The Unico System also reduced the daily average relative humidity levels in the home by 13% versus the conventional 22 SEER unit. (Fig. 3) In separate laboratory tests, Unico cooling coils have been demonstrated to remove up to 30% more moisture than conventional A/C coils.

Because of its ability to significantly reduce relative humidity levels, occupants feel more comfortable at higher thermostat settings, allowing for reduced operation and resulting in significant energy savings.

Consumers should bear in mind that SEER ratings are based on equipment performance in static laboratory tests and not with systems attached to ducting in actual real-world

Fig. 2: Unico AHU vs. conventional AHU performance1

situations. When full-system head-to-head performance tests in actual environmental conditions are performed, The Unico System consistently out-performs conventional systems with higher SEER ratings when it comes to energy efficiency, humidity removal and duct superiority (click here to view our eBook on The Unico System’s ductwork performance).

Reference/attribution:1 Variable Capacity Comfort Systems and Smart Ventilation Systems in High-Performance Homes – Florida Solar Energy Center <Will link to study when it is up on Unico’s website>

Fig. 3: Relative humidity control of Unico System vs conventional system1