The Challenge

Why Mid-Rise and High-Rise Apartment Buildings Waste Energy

There are several reasons why heating energy is wasted in multi-family residential buildings, including the following items that make it difficult to control space temperatures:

What you see

What you see

  • When air is heated it rises. There are duct and pipe shafts, elevator shafts, and stair wells that allow air to move upward inside a building.
  • As heated air rises in a building it creates a negative pressure that draws in even more outdoor air particularly at lower floors.
  • Electric baseboard heaters are usually over-sized for the required heating load since they have fixed increments of capacity and must have equal or greater capacity than the required heat loss.
  • The overcapacity problem becomes even worse when the outdoor air temperature is not sub-freezing, which is most of the heating season.
  • Electric baseboards are normally fully ON or fully OFF. Their output does not match the heat loss.
  • Some occupants adjust their thermostats up or down to suit how they feel.
  • Some occupants are used to or prefer high thermostat settings.
  • Interior walls and floors of apartment units are not insulated, so that an adjacent overheated space also overheats the surrounding spaces.
  • What you don't see

    What you don't see

    The usual reaction when one’s space is to warm is to open a window. Cool air enters if the window faces the wind, but air may only exit on the other exposures.

  • Open windows on all but the lowest floors encourage even more heated air to rise in the building, drawing in even more outdoor air at the lower levels.
  • Some of these reasons apply to buildings with gas heat also, even where each unit has its own furnace.