Energy Audit & Payback Lab
Build a sub-metered picture of where a building uses its energy, price it on DEWA slab tariffs or a flat NZ or Australian rate, then test the usual savings: LED lighting, lighting controls, variable speed drives on pumps and fans and a higher cooling setpoint. Get annual savings, simple payback, a 10 year cash flow and the carbon saved.
How to use: enter or edit the sub-meter loads, check the tariff, then tick the measures to test. Prices and slabs are editable defaults: confirm the current DEWA or retailer tariff. Tap i for help.
1. Inputs
2. Where the energy goes
Breakdown before and after, a 3D year by month and the cumulative cash flow.
3. Checks
4. Measures and payback
5. Monthly bill
Average month. Cooling follows the season, so real summer bills are higher.
6. How it works
Start with the meters
An ASHRAE Level 1 walk-through or a Level 2 audit (ISO 50002) begins by splitting the main meter into end uses: lighting, cooling, pumps and fans, small power and lifts. Sub-meters or short term loggers give the kW and the hours. In Gulf buildings cooling is usually more than half of the bill.
Slab tariffs
DEWA bills each account on slabs: the first block of kWh each month is cheaper and the rate steps up after each slab, plus a fuel surcharge and VAT. Savings come off the top slab first, so each kWh saved is worth the highest rate you pay. In New Zealand and Australia most commercial customers pay a flat energy rate plus daily and demand charges.
Typical measures
LED fittings cut lighting power by 40 to 60%. Occupancy and daylight sensors cut the hours. A pump or fan at 80% speed needs only about half the power (affinity laws), so VSDs pay back fast where flow can drop. Each 1°C higher cooling setpoint saves about 3 to 5% of cooling energy.
Indicative audit tool. Use measured data, the current tariff from DEWA or your retailer, and contractor prices before committing to a project.