The principle
Recovery is small in isolation. It is significant when it is aggregated, stored and dispatched.
Any one of the three HERS pathways, sold on its own, produces a disappointing business case. A turbine in a water riser makes a few hundred watts. A regenerative lift drive pays back over a decade if you count only the kilowatt-hours. Heat recovery is worth little unless there is a hot water load to absorb it.
What changes the arithmetic is the bus. Once the three streams share a DC link with a battery and a controller, their combined output stops being background trickle and becomes something the building can aim: at the 2 p.m. demand peak, at the chiller's startup inrush, at the EV chargers in the basement. Under the restructured RP4 tariff, a kilowatt of avoided maximum demand is worth roughly as much per year as three hundred kilowatt-hours of avoided energy. HERS is designed around that asymmetry.
The second thing the controller does is arguably more valuable than the first. Every recovered joule is metered at the point of recovery against an IPMVP Option B baseline, which means the building's sustainability report is no longer an estimate built from utility bills and spreadsheets. It is instrumented.
The control layer
Under RP4, when you use a kilowatt matters more than whether you use it.
Maximum demand is now billed twice — once as capacity, once as network — at a combined RM89.27 per kW per month on Medium Voltage General. A single half-hour of careless coincidence sets that charge for the entire month.
Dispatch, not trickle
- Predictive peak forecasting from lift traffic, chiller staging and occupancy, so the battery is charged before the peak rather than during it.
- Recovered power is prioritised to coincident loads first, storage second, export never — avoiding licensing complexity.
- EV charging in the basement is curtailed and re-profiled rather than blocked, using OCPP 2.0.1 smart charging profiles.
Metering that will survive an audit
- Class 0.5S revenue-grade metering at each recovery point and at the point of common coupling.
- IPMVP Option B retrofit isolation — savings measured, not estimated from a whole-building regression.
- Immutable half-hourly record retained for the full disclosure period, exportable to Bursa's Centralised Sustainability Intelligence platform format.
Built to Malaysian code
- Switchgear and assemblies to MS IEC 61439; installation under the Electricity Supply Act 1990 and Electricity Regulations 1994.
- Competent-person sign-off and Suruhanjaya Tenaga notification handled as part of commissioning.
- EV charging interfaces to MS IEC 61851 where the DC bus serves chargers.