Submetering: A Continuum from Measurement to Estimation
The term “submetering,” as commonly used, has come to mean a process for transferring legal responsibility for utility usage to individual residents in multifamily and other multi-unit properties.
Although the term includes the word “meter”, submetering can also include utility allocation processes that do not utilize meters but instead are based on formulas that estimate utility usage. Along the continuum from measurement to estimation are hybrid systems which rely on a combination of measurement devices and allocation formulas.
- Hot Water Allocation
Submeters manufactured to specifications established by the American Water Works Association and American National Standards Institute provides dependable, accurate measurement of utility usage. Advanced metering technologies incorporate radio frequency devices which electronically read utility submeters and transmit the readings on a daily basis to a bill processing facility.
Hybrid systems are used in situations where metering devices will capture only a part of each unit’s utility usage. For example, in some apartment communities the plumbing system will allow submeters to measure only a portion of water used in each dwelling unit. The most common partial capture application is to install a submeter on the cold water line feeding the water heater. This type of “partial capture” submetering is also called Hot Water Allocation Submetering. The term "allocation" is used because a portion of each resident's water bill is based on the allocation (or estimation) of cold water usage. The term "hybrid" refers to the fact that this type of submetering is based on both metered and formula allocated usage.
Gas Runtime Allocation is a very specific hybrid system. Many existing apartment communities were originally constructed with heating systems that do not permit individual metering of gas usage. In these communities, high-resolution sensors can be installed to measure the runtime of gas-fired furnaces, hot water heaters and fireplaces. Runtime monitors can also be installed to estimate baseboard heating costs. In both of these applications, distribution losses, standby heating and other unmetered cost are allocated back to individual residents based on a mathematical formula.
Formula billing uses a mathematical formula to estimate utility usage in each apartment unit. A commonly used form of allocation billing is called Ratio Utility Billing Service. RUBS is a form of allocation billing in which the utility charges are based on a formula that takes into account several factors including number of residents in each dwelling unit, the size of each unit, common area usage, master utility usage, occupancy days and the number of water fixtures in each unit. Flat fee billing typically divides utility usage equally among all residents.