DOAS + Heat Recovery

V+ H/AC > HVAC: HOW SEPARATING VENTILATION FROM HEATING AND COOLING WHILE ADDING HEAT RECOVERY PROVIDES BETTER AIR QUALITY AND COMFORT ALONG WITH ENERGY SAVINGS

Why Traditional Systems are Inefficient

Traditionally in North America, systems for heating, cooling and ventilating buildings combine all three functions into a single system that heats and cools by moving air from a central heating/cooling unit throughout the building. Fresh air for ventilation is introduced into the system from the outside. This approach has built-in inefficiencies:

  • Air is a poor conveyor of heat. It takes a relatively large amount of hot or cool air moved throughout the building to maintain a comfortable temperature, especially during extreme weather conditions.
  • The fan energy required to blow this air through ductwork is considerable.
  • Building codes, and standards, specifically ASHRAE 62.1, require minimum fresh airflow. All of this air must be heated or cooled to desired indoor temperature

Without heat recovery, when air is brought in from the outside to meet ventilation standards, energy is required to heat or cool the outside air to the desired inside temperature. In systems that cannot match fresh air intake to demand, ventilation must always meet peak demand when occupied, so more outside air is conditioned than is demanded, further wasting energy.

Finally, a central heating and cooling system often leaves some areas too cold while others are too hot. They fail to deliver comfort to occupants.

Diagram of Traditional Heating and Cooling System
Ventacity Split Systems Diagram

A NEW, EFFICIENT APPROACH: SPLITTING VENTILATION FROM HEATING AND COOLING

A split Ventilation + Heating/Air Conditioning system takes a different approach. In it, a dedicated outdoor air system (DOAS) supplies only the outdoor ventilation air necessary to maintain high ventilation standards, while independent heating and cooling coils inside the building take care of conditioning the space.

Since a smaller volume of air needs to be moved in a split system, (reduced load) a smaller capacity air handling unit can be used, reducing the fan energy consumed. And since the amount of outside air introduced can be modulated for demand, less air is needed for heating and cooling, resulting in further energy consumption savings.

Further efficiencies can be gained by adding heat recovery to the ventilation system. With a heat exchanger built into the ventilator, heat flows between the intake and exhaust air streams so that a large percentage of the heat in the building is retained in winter or kept outside in summer, further reducing the energy required for conditioning air.

Ventacity Systems VS 1000 RT intelligent HRV with its 93% heat exchanger efficiency (vs 65% efficiency of other products) delivers fresh air at just a few degrees above or below the inside air, resulting in “draft free” ventilation and enhanced comfort as well as improved energy savings.

Ventacity Energy Savings

Finally, since heating and cooling occurs in specific zones within the building, more precise temperature control is possible and allows for maximum comfort while reducing excess heating or cooling.

In summary, the VS 1000 RT reduces the energy load on the building, consistently serves healthy air in compliance with ASHRAE 62.1 and meets any code requirements for an economizer, enabling a much more efficient heating and cooling system that is smaller, more environmentally-friendly and typically cheaper than other systems.

BUILDING ASSESSMENT

Contact us today for a complimentary building assessment and find out how we can help you save money as well as reduce the environmental impact of your energy system.