Underground Garage in Multifamily Housing—getting a handle on life cycle cost

The Center for Sustainable Building Research (CSBR) in conjunction with Minnesota Green Communities held a workshop in November of 2014 to explore the impact of energy and cost associated with underground garages in multifamily housing apartment buildings. The work hoped to address the large impact garages have on both first cost and life cycle cost, which as buildings become more efficient accounts for an increasing larger percentage of total building utility cost. The goal of this work is to understand and propose solutions to create energy efficient garages, and suggest alternatives new construction projects in cold climate that are having difficulty meeting EnergyStar requirements. This is primarily due to the requirement for unheated garages and plenum spaces. Concerns stemming from these mandates are pipe freeze, surface icing, safety, and market perception. The work considered technical solutions examining both alternative design solutions (design for smaller loads), and alternative mechanical solutions (efficiency).

The workshop led to three avenues of inquiry exploring; (1) alternatives parking configurations; (2) alternative designs for unheated garages; and (3) alternative mechanical systems to achieve deep energy savings. A discussion of each exploration follows below. The summary recommendations stemming from the explorations include the following:

  • Eliminate snow melt systems whenever possible (16% total building energy savings)
  • Carbon Monoxide (CO) sensor control of garage ventilation fans (80% savings for garage energy)
  • Occupancy controlled LED lighting (79% savings for garage lighting)
  • Right size parking (energy cost for a code based garage are $400/stall)
  • Insulate the common garage ceiling and first floor to meet ASHREA 55 standards
  • Reduce set points 5F to 40F (10% savings for garage energy)

Status: complete