In an ideal world we have an electrical meter for each tenants and many more to monitor all building systems (HVAC, lighting, hot water…) which are shared among tenants. This means that a building with 50 tenants would need 60 to 75 meter which could cost more than $75,000 to install. This is quite an investment so is there a less expensive way to do it? Yes, there is as described below.
1-Electrical Meter for Tenant Billing
As each tenant will have different energy consumption profile (kWh/m2), it makes sense for equity reason to monitor their electrical consumption and bill them individually. Installing an electrical meter for each tenant can be very expensive. Sometime a single meter will not monitor all the energy consumed by the tenant if, for example, the HVAC or hot water is provided from the building main system. In these cases, additional meters will be needed to estimate the tenant share usage of the building common systems.
Here are some possible ways of reducing the number of electrical meters needed
1- Estimate the electrical consumption of tenant with low electricity usage (ex: less than $2500/yr). Based on the installed electrical load, it is possible to estimate the energy consumption with an 85% to 95% accuracy.
2- Estimate the electrical consumption of tenant with low monthly variation of their energy usage (Ex: the tenant yearly electricity consumption has the lowest month consumption at $2000 and highest month at $2500. It is possible to estimate the energy consumption with an 90% to 95% accuracy.
3- Use the data (running time, power, amperage…) provided by automated systems (intelligent systems) such as HVAC control system, centralised lighting control system to estimate the electrical consumption.
4- Take sporadic power consumption measurement at strategic time of the day, weekend and season to estimate the power consumption.
5- Only meter the electrical loads that are fluctuating over time and estimate the ones that are constant
6- Monitor (install meter) the building main systems only and distribute the energy cost of each system to the tenants based on, hour of operation, kw installed, cfm installed…
With a combination these methods and others it is possible to reduce the required number of electrical meters significantly and reach an accuracy in the 90% to 95% range. At EnergyToBill we can survey your building and provide you suggestion and cost estimate for monitoring your tenant electrical consumption in a cost-effective way. EnergyToBill can also provide Metering-As-A-Service where the meters are leased to you on a monthly basis with long term service agreement. For large buildings (>50000 square feet) the Metering-As-A-Service including monthly electrical consumption billing to the tenants can cost less that 2% of your electrical bill (subject to site survey).
2-Electrical Meters to Monitor the Building Main Systems
Typical building main systems are HVAC (heating, ventilation, air conditioning system), lighting, hot water, power outlets, process equipment (motors, compressor, hydraulic units, heaters…). These systems can be metered for:
2.1 Energy Saving Purposes
The first step in an energy reduction program is to understand how the energy is consumed by each building system in function of the day, the weekend, the season, the outdoor temperature, the occupancy of the building etc….. Then by comparing each system energy consumption with best in class we can you determine what are the potential savings, what should be the priorities, what target to set and how we will monitor the progress and make adjustments as we go along. The number of electrical meters needed to accomplish this task can be reduced by:
1- Only meter the loads that are fluctuating over time and estimate the ones that are constant.
2- Take sporadic power consumption measurement at strategic time of the day, weekend and season to estimate the power consumption.
3- Use the data such as number of hours used, amps and power provided by the building automated systems (intelligent systems) such as HVAC control system, centralised lighting control system to estimate the electrical consumption.
4- Use meter only for the large systems consuming most of the energy.
With a combination these methods and others it is possible to reduce the number of electrical meters significantly and have enough accuracy to take the appropriate steps in order to achieve our energy saving goals. At EnergyToBill we can survey your building and provide you energy saving suggestions along with an estimate of the investment cost and potential savings. EnergyToBill can also also provide Metering-As-A-Service where the meters are leased to you on a monthly basis with long term service agreement.