Occupancy Sensor Savings Calculator

Maths can be found here.Occupancy Sensor Calculator

Occupancy Sensor Calculator

Facility Specific Input

Electricity Unit Cost ($/kWh): Enter the cost of electricity per kilowatt-hour in your area.

Demand Unit Cost ($/kW): This is the cost your utility charges for the highest 15- or 30-minute average power demand (in kilowatts) during your billing cycle. It's separate from the per-kWh energy charge. It is not needed if you are not using light at peak demand or if you are only interested in kWh savings.

Labor Rate ($/hour): Enter the average hourly labor rate for maintenance personnel.

Carbon Intensity Electricity (lb-CO2/kWh): This represents the amount of CO2 emissions (in pounds) associated with generating one kilowatt-hour of electricity. This is used to calculate the CO2 emissions you save. If you only care about cost savings, use the default. For the US, average values can be found on the EPA site; use the value associated with your region.

Do these lights operate during peak demand? "Peak demand" refers to the period when electricity usage is at its highest. Select 'Yes' if the lights in this zone are typically ON during your facility's peak demand period. This affects demand cost savings.

Zone Operating Hour Specific Input

Operating Hours per Day (hours/day): Enter the average number of hours per day the lights are on.

Operating Days per Week (days/week): Enter the number of days per week the lights are typically on.

Operating Weeks per Year (weeks/year): Enter the number of weeks per year the lights are typically on.

Occupancy Sensor Specific Inputs

% of Fixtures in Zone to be Controlled by Occ. Sensor (%): Enter the percentage of fixtures *in the zone* that will be controlled by occupancy sensors.

Fixtures per Occ. Sensor (fixtures/sensor): This is the *average* number of fixtures controlled by a *single* sensor. For example, if one sensor controls two light fixtures, enter '2'.

Occ. Sensor Installation Time (hr/sensor): Enter the average time to install *one* sensor (in hours). Include any wiring or configuration time.

Choose Input Method: Select how you want to estimate the reduction in lighting hours: either by the percentage of time the space is occupied, or by directly entering the reduction in operating hours.

% of Time Occupied (%): Enter the estimated percentage of time the zone is typically occupied while the lights are normally on. For example, if the lights are on for 8 hours, and people are present for 4 hours, enter '50'.

Reduction in Operating Hours per Day (hours/day): Enter the *reduction* in daily operating hours due to the occupancy sensors. For example, if the lights are currently on for 8 hours, and the sensors will reduce this to 4 hours, enter '4'.

Cost of Occupancy Sensor ($/sensor): Enter the cost of a *single* occupancy sensor.

Fixture Specific Input

Number of Fixtures in Zone (fixtures): Enter the total number of light fixtures *in the zone* you are analyzing.

Fixture Ballast Factor: The ballast factor is a multiplier representing the light output of a lamp-ballast combination relative to the rated output. A value of 1.0 means the ballast operates at the lamp's rated output. Values less than 1.0 indicate reduced light output (and often, reduced power consumption).

Number of Bulbs per Fixture (bulbs/fixture): Enter the number of bulbs in *each* light fixture.

Bulb Wattage (W/bulb): Enter the wattage of *each individual bulb*.

Bulb Life (hours): Enter the rated life of the bulbs in hours. This is usually printed on the bulb or its packaging.

Bulb Replacement Time (hours/bulb): Enter the average time it takes to replace a *single* bulb (in hours). Include any time spent retrieving the bulb, setting up a ladder, etc.

Bulb Cost ($/bulb): Enter the cost of a *single* replacement bulb.

Financial Analysis Input

Energy Escalation Rate (%/year): Enter the projected annual percentage increase in energy costs (used for IRR calculation). If you don't want to project future energy cost increase, you can enter '0'.

IRR Calculation Period (years): Select the number of years over which to calculate the Internal Rate of Return (IRR).

Results

Lighting Specific Calculation

Current Lighting Hours per Year:

Proposed Lighting Hours per Year:

Power Consumption per Fixture:

Total Lighting Power Consumption:

Current Electrical Consumption:

Electrical Consumption with Sensors:

Demand Savings:

Electricity Savings:

Demand Cost Savings:

Electricity Cost Savings:

Carbon Emissions Savings:

Maintenance Specific Calculations

Current Bulb Replacement Material Cost:

Current Bulb Replacement Labor Cost:

Proposed Bulb Replacement Material Cost:

Proposed Bulb Replacement Labor Cost:

Material Costs Savings:

Labor Cost Savings:

Savings Calculation Summary

Demand Savings:

Electricity Savings:

Carbon Emissions Savings:

Total Cost Savings:

Implementation Cost, Payback, and IRR

Implementation Material Cost:

Implementation Labor Cost:

Total Implementation Cost:

Simple Payback:

Internal Rate of Return (IRR):