Energy Saving Benefits
The Energy Saving Benefits of Aristotle-Air Heating & Ventilation Systems
Addressing the Current Energy Issues in Our Classrooms
Fuel Costs: Outside air in the winter is often 20 – 40 degrees F below the inside air temperature (in some zones it can actually reach over 70 degrees F below indoor air temperature). To maintain a comfortable room temperature, a traditional unit ventilator requires a tremendous amount of energy to increase the air temperature before it is delivered to the room (at approximately 110 degrees F). This requires the boiler system to be continuously cycling hot water to the unit for it to maintain a comfortable classroom temperature. This continuous cycling is both expensive and increases wear and tear. Additionally, traditional units also require continuous hot water cycling, because they get so cold they are susceptible to freezing.
The Aristotle-Air system is designed and engineered to extract heat from inside air. This is the most significant difference between the two system designs. Since ambient air is approximately 68 degrees F, it requires much less energy to use it to maintain a comfortable room temperature. Heating the room with indoor air is achieved by capturing the heat from the ambient air before it is exhausted outdoors. The system is designed to have the indoor air flow into a heat exchanger when the thermostat calls for heat, before the air leaves the building.
As air flows toward outdoors, the air in the heat exchanger passes the incoming fresh air coming from the other direction. Heat from the outgoing air is absorbed by the incoming air, raising its temperature. The two never mix together, but only flow next to each other in opposite directions. In this process, the incoming air is “pre-heated” before being brought up to a preset temperature by the heating coils.
This more efficient, on-demand heating system provides significant benefits:
1. Smaller boilers can be employed that operate at higher efficiency levels (saving energy)
2. Smaller pipes (costing much less) can be used with an Aristotle-Air system
3. Continuous hot water cycling is not required for operation (saving energy)
4. Air temperature only needs to be raised minimally to be at comfort level (saving energy)
Healthy Energy Resources is currently the only U.S. manufacturer that incorporates this passive heat recovery technology in classroom unit ventilators.
Economy Mode: When a room is unoccupied, the Aristotle-Air unit goes into “economy mode” and recycles ambient air when heat is called for, minimizing the energy required to raise air temperatures throughout the nighttime hours.
Air Intake Issues: A traditional classroom unit ventilator employs over 1000 square inches of building envelope penetration. This basic design hasn’t changed since the 1950’s, and is typically comprised of a louver measuring 56.5” X 11” (621 square inches) for outside air intake and an exhaust ventilator measuring 20” x 20” (400 square inches). This combination of room openings represents a massive amount of air infiltration, well beyond what is necessary, and it directly impacts energy usage.
Compare those openings to the Aristotle-Air intake and exhaust system that incorporates only two circular 8-inch intake openings in the building wall (roughly 10% of the traditional classroom unit). Multiply that figure times the number of classrooms in a typical school and this represents a massive reduction in outside air penetration.
An even more significant problem is found in older heating systems. Upon inspection, these large, outside air dampers are commonly found to be inoperable, blocked with debris, stuck wide open, or stuck shut. This results in either too much or insufficient ventilation, impacting all sides of the energy efficiency equation. In addition, when dampers are stuck in a closed position, very high CO2 levels in the classroom are produced– levels that exceed ASHRAE standards and impact the learning environment*.
*(See: Wargocki, P., D.P. Wyon. 2006 “Effects of HVAC on student performance.” ASHRAE Journal (10):22-28)
Air Leakage Issues: The older, traditional unit ventilator dampers are often found to be warped and therefore cannot seal properly (in fact, this problem is so common that most energy audit software allows for a 4% outside air infiltration loss factor). Continuous air leaks consequently increase demand for heating during the winter months. Air leakage also causes the system to run unnecessarily and increases wear and tear on components.
The Aristotle-Air unit addresses this issue with two 8-inch circular dampers that seal with 20 lbs. of torque. This damper system insures there will be no unwanted outdoor air infiltration.
Fresh Air Ventilation: Any factor over 500 CFM is well beyond what is required to bring an ample supply of fresh air into a classroom. The Aristotle-Air unit produces 425 CFM in fresh air mode, well within ASHRAE engineering guidelines*.
* See ASHRAE Standard 62
Noise Comparison: The Aristotle-Air unit ventilator in full heating operation produces noise levels equal to the units of the other major manufacturers (52 Db for horizontal units, less for ceiling units).