Evaluation of the Multi-Family Pilot Project

In the fall of 1984 Minnegasco and the Minneapolis Energy Office (MEO) initiated the Multifamily Pilot Project (MFPP) to demonstrate the effectiveness of an energy conservation installation program for multifamily buildings. While a Minnegasco sponsored energy audit service has been available for 5 plus multifamily buildings owners through MEO since 1982, the MFPP was the first attempt to incorporate the installation of recommended retrofits into that service. This approach was expected to produce the highest implementation of needed conservation measures and hence save the most
energy.

The goal of the MFPP was to install outdoor reset and cutout controls in up to 50 hot water multizone buildings with cast iron boilers and to install a steam balancing control system developed by MEO in up to 50 single pipe steam heated buildings. Since the steam control system was a recent development a further purpose of the project was to refine steam balancing technology. Mechanical system improvements were the focus in the MFPP because in general they have much faster paybacks than structural retrofits in multifamily buildings and because they are much more likely to be affordable to owners without deep subsidies. In addition to this work, all buildings with showers were eligible for low flow showerheads.

Participants in the MFPP were owners of multifamily buildings who either had previously received an energy audit with the specific recommendations targeted for this project or were in the process of receiving such an audit. Of previously audited building owners who were contacted, only about 28% had completed the targeted recommendations on their own. An additional 48% completed the work as a result of the MFPP. The total number of original participants in the project was 57 of which 19 were hot water multizone buildings and 38 were single pipe steam buildings. Of the 19 hot water buildings, 18 reset and cutout installations were successfully completed. Of the 38 steam buildings, 29 had successful installations of steam balancing control systems.

Gas consumption before and after the installations was analyzed to determine savings in 8 of the hot water buildings and 13 of the steam buildings. Overall savings for the reset and cutout installations was 9%. The average cost of installing these measures in the 8 buildings was $615 per building and the median payback for the analyzed group was 1.9 years. Average savings among the 13 steam buildings analyzed was 10%. The average cost of the retrofit for the 13 cases was $1150 per building with a median payback of 1.3 years.

Future implementation of a reset/cutout installation program is straightforward. The device works well, is a known technology and offers owners a good return on investment. As a result, MEO is now offering a special Minnegasco sponsored program to hot water multizone building owners which includes a seminar, energy audit and installation program. Future analysis and field work is also planned to resolve technical issues around techniques for determining the ideal reset ratio for each building.

A successful steam balancing strategy was developed, tested and shown to be quite effective, but a program for future implementation of steam balancing controls is not as straightforward. Such a program should offer a comprehensive audit, thorough specifications and a follow-up balancing service. Ideally, there should also be active owner/caretaker participation in the balancing process. Through the 1986-87 heating season Minnegasco and ME0 will be offering a steam balancing service on a limited basis to determine the specific implementation details of a program that can then be actively marketed by the Fall of 1987.

During the course of the MFPP many problems were encountered and solved. The experience gained as a result of this pilot is an irreplaceable contribution to Minnegasco's ability to offer multifamily building owners reliable information, services and programs that will reduce energy consumption in the future.

Full Report (PDF)
Evaluation of the Multi-Family Project