BY ROBERT A. FRIESS, AMPS and MONA SHYMAN, MHS ASSOCIATES

This article will explain why residential buildings in New York City should install electrical submetering. Submetering is the process of allocating electrical energy costs on an apartment basis. Usually this is performed by metering the energy consumed per apartment and billing the individual tenant or owner for the energy consumed. In this manner the owner/tenant is financially responsible for the electrical energy consumed in their apartment. Most older apartment complexes in New York City were built as master metered buildings with the building paying the energy costs for all owners/tenants in the building.

Submetering involves the installation of either an electromechanical or solid state meter which monitors the energy consumed in the apartment being metered. The old style electromechanical meters can either be read manually or equipped with an "encoder" so that the meter can be read remotely by telephone. Present state of the art solid state meters utilize power line carrier technology and are read remotely using telephone communications. Depending on how a building’s electrical distribution system has been installed, the individual apartment meter can be installed in the building basement, the meter room if provided, or the individual apartment. Installation of the meter in an apartment can usually be accomplished with little inconvenience to the tenant/owner and looks just like the present circuit breaker/fuse box in the apartment.

Having briefly explained what submetering is, we can now discuss the objective of this article, why should a building install submetering? Submetering accomplishes two (2) main objectives.

WHY SUBMETER?

The first key point is that with submetering each tenant/owner only pays for the energy they consume, no more or no less. In a traditional master metered building, the total energy costs for the building are allocated across the number of apartments in the building. This allocation can be based on numbers of shares, apartment size, apartment location in the building or some other criteria established by the board or owners of the building. Usually, under this allocation system, larger apartments pay a high share of the electric costs than smaller apartments.

We have performed pilot submetering studies in a number of buildings and this has shown that this method of allocation is not always fair and correct. Figure 1 shows the average weekly energy consumed in a Manhattan cooperative building. The studied was conducted using a sample of 30 apartments and no apartment in the study was aware that it was being submetered. Building management chose which apartments would be used for the study. The apartments included low users of energy, average users of energy and a number of abusers of energy consumption.

Figure 1 shows that three out of seven 5.5 room apartments used less energy than the smaller apartments in the building and a number of 2.5 and 3 room apartments used as much energy as some larger apartments. Figure 2 shows the same data with the average usage for each apartment size also on the chart. This table shows that averaging apartment size provides a distribution indicating increased electrical usage with increase in apartment size. Clearly the data presented in Figures 1 and 2 indicates that averaging usage over the number of apartments in a building, even when you account for the apartment size in the averaging method, may be unfair to individuals in the building. A number of apartments are paying for energy they do not consume.

A study of submetered buildings indicates that when a building is submetered, approximately one third of the apartments pay less for energy, one third of the apartments pay the same for energy and one third of the apartments pay more for energy. Figures 1 and 2 support our first key point which is that with submetering, a tenant or owner only pays for the energy they consume.

ENERGY CONSERVATION

The second key point of submetering is that it achieves conservation of electricity thereby reducing the costs for the tenant or owner of the apartment. The New York State Energy Research and Development Authority has performed a detailed study of residential submetering. This report states the following:

1. Submetering saves energy - An analysis of submetered buildings (where data has been made available) conclusively illustrates that annual savings of 10-26% of total apartment electric consumption were achieved in the first year of submetering.
2. Submetering energy savings persist over time - Submetering savings have been proven to be maintainable over long periods of time as demonstrated in a number of studies that were performed. Table 1 provides data from three buildings that were submetered. Some likely reasons are (a) that conservation is reinforced each month by the resident’s receipt of an electric bill: and (b) residents will invest in efficiency (e.g. more efficient refrigerators and lighting) because they will reap the benefits directly.

The above conclusions clearly show that people will conserve energy and pay less if they are billed for it directly and they can control its use. If they do not conserve energy, or abuse the use of energy they consume, they will pay for this privilege. The data presented in Table 1 clearly shows that a building and its owners can save money, and this savings can be maintained over an extended period of time.

SAVE MONEY

Submetering can save a building and its owners or tenants money. The savings to be achieved, and the costs to achieve these savings are building specific issues. These should be discussed with a submetering professional who can determine if submetering is a viable alternative for a specific building.

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