How Susten rebuilds a cooling plant.
The technical detail belongs here: what we instrument, how the plant is designed, how controls are written, and how zero-capex commercial models work.
Read this when you need to understand what changes physically, digitally and commercially.
Most ESCOs resell a chiller. We design one.
A typical energy services firm buys equipment off the shelf, installs a vendor's control package, and hands you a report. We own the whole stack, which is why the numbers still hold years later.
Audit the real load
We inspect the plant, bills and operating profile, then fix the baseline before anything is specified.
Design the plant and controls
Chillers, pumps, towers, air-side equipment, PLC logic and metering are designed as one system.
Fund and rebuild
Susten or an investor carries the equipment cost. The building stays occupied while the work is staged.
Operate and verify monthly
The EMS watches the plant continuously; monthly M&V reports decide savings and invoices.
Chillers designed to your load
We design the machine around your building's real consumption profile and this climate, rather than fitting your building to a catalogue unit.
Typical ESCO: resells an OEM unit as specified.
Control logic written in-house
We buy controller hardware off the shelf but write the entire PLC logic ourselves. The strategy is ours, tuned to the plant we designed, not a vendor default nobody revisits.
Typical ESCO: off-the-shelf vendor control packages.
Our own cloud EMS
Thousands of sensors feed our platform, where AI flags equipment drifting outside normal parameters before it becomes a breakdown. Monthly reporting is non-negotiable.
Recognised with a Steward Leadership 25 award, 2025. See what we meter, and how savings are settled.
A cooling plant throws away heat that a building is paying to make.
Every chiller rejects heat to a cooling tower. In a hotel, a resort or a hospital, the same building is simultaneously burning gas or electricity to heat water. Those two facts sitting in one plant room are an obvious piece of waste, and recovering it is the same discipline as everything else we do.
Efficiency is set by the lift.
A heat pump's efficiency depends on the gap between where it takes heat from and where it delivers it. From the condenser water return, at roughly 30 to 33 °C, up to 55 °C, that gap is about 25 K. From the chilled water return it is about 45 K, nearly double.
It turns the machine into a bad chiller.
Drawing from the chilled water side means the heat pump is also doing cooling, at well over 1 kW per ton against roughly 0.6 for a decent water-cooled plant. You would be displacing efficient cooling with cooling that costs more than twice as much.
The saving counts twice.
That heat is already on its way to the cooling towers. Taking it makes hot water at a high coefficient of performance, and it lowers the temperature the chillers have to work against, so the chiller plant itself runs better. One intervention, two savings.
You do not fund the equipment.
Every client we have worked with has wanted zero capital outlay. Both models are built for that.
Energy Performance Contracting
PrimaryWe fund and deliver the project, then take a share of the energy savings generated over a long-term contract. You keep the remainder from the first month.
- Cash-positive from the first month of operation
- We are paid only out of savings actually delivered
- Susten carries the performance risk, not you
Cooling as a Service
DeliveredAn investor funds and owns the cooling system we design and build. You avoid the capital cost entirely and pay for the cooling you use, metered and billed like a utility.
- You pay per unit of cooling delivered
- Susten operates against a contractual efficiency guarantee
- In service today on a live hypermarket site