Multi-Family Housing - Apartments
Of the 106 million housing units in the U.S, 19 million, or 18 percent, are multi-family. In the Gulf Coast Region, there were about 10.3 million housing units in 2005, of which 1.7 million were defined as multi-family units defined as buildings with five or more units as defined by HUD (approximately 16% of total housing in the region). Table 1 below describes all multi-family housing in the Gulf Coast Region.1


Nationally, multi-family buildings are, for the most part, occupied by renters. This trend is echoed in the Gulf Coast Region as well, with 94% of all multi-family housing units occupied by renters as shown in Table 2.1


The amount of energy used in multi-family buildings varies, depending on their condition, age, original design, or controls and policies - such as whether tenants in rental buildings pay their utility bills as part of their rent or pay it separately based on their energy use. Overall, residential housing accounts for 22 percent of energy use in the United States. Of that amount, 72 percent is accounted for by single-family housing and 28 percent by multi-family (more than 2 units).1

On whole, multi-family buildings tend to be less energy intensive than single-family homes, as shown in Figure 1. The reasons for this difference are the comparatively smaller wall and roof space and the smaller size of units within multi-family buildings.1


In 2005, installed CHP capacity in apartment buildings was estimated to be 70.4 MW at 150 sites across the U.S.3 Overall, natural gas is the most common fuel used in these systems. Reciprocating engines, fuel cells and micro-turbines are the most common prime movers used.

In 2005, the potential for additional CHP in apartment buildings was estimated at 11,600 MW nationally.3 The table below shows the breakdown of this potential by both CHP system size and number of apartment buildings.


Residential cogeneration systems work best in large buildings with heavy power demands. The buildings with the highest potential for energy savings are multi-family dwellings (approximately 100 apartments or more) that have high electrical and heating usage for 16 hours a day or more, six days a week.2