Achieving energy efficiency with modern school construction
One of the considerations given with the new construction currently under way in our schools is the importance of balancing indoor air quality with energy efficiency.
Indoor air quality affects not only the health of students and faculty, but comfort levels necessary to foster an adequate learning environment.
A challenge in balancing efficiency with comfort levels in school buildings is the required amount of outside air necessary to be brought in for optimal indoor air quality. In response, significant upgrades are being implemented to current ventilation and mechanical systems.
New, more effective air handling units use exhausted air to re-heat the incoming outside fresh air. On extremely cold days such as we have been experiencing, it requires less energy to heat the outside air coming in by using exhausted air pulled out of the building already at room temperature that helps maintain heat in the equipment warming the incoming outside air.
Another issue to factor in is temperature control. Buildings primarily composed of concrete hold a thermal mass of hot or cold, depending on outside temperatures, that is slowly released over several hours. With outside temperatures changing up to 50 degrees or more overnight in our climate, additional challenges are presented in achieving proper balance.
In addition, several hundred individuals within the building and the resulting impact of their body heat, as well as heat that is lost through windows, doors and walls, all impact indoor building temperatures.
Doors left open or repeatedly opened at the start and end of the school day for several minutes in subzero weather quickly cool down hallways. To counteract this effect, new air lock entryways have been incorporated into the building plans that will trap cold air before it enters the main building.
Further energy effectiveness has been achieved with the replacement of the original school boilers installed in 1965 offering approximately 75 percent efficiency with new, 99 percent efficient boilers.
This means a difference of 25 percent heat loss versus a 1 percent heat loss through exhaust.
Other improvements have been achieved with the addition of increased roof insulation, insulating exterior walls and replacement of old, inefficient exterior windows and doors.
Energy proficient lighting, motion detectors to turn lights off in unoccupied areas and variable speed drives on most motors operating air handlers and heating pumps, as well as the installation of energy efficient water heaters are all examples of some of the efforts that have been implemented to maximize efficiencies resulting in overall, long term cost savings.
Our district is very fortunate to have the modern upgrades that will benefit the school district and community for years to come.
(Mark Mortenson is director of buildings and grounds for the Pequot Lakes School District.)