Measure
Don't estimate performance. Measure it.
Temporary instrumentation establishes how equipment actually performs under real operating conditions, starting with central cooling plants. Continuous commissioning returns to audit so the plant is not left to drift after a single study.
Methodology
How we measure plant performance
Equations, component budgets, and instrument uncertainty so engineers can see the method, not only the marketing.
System efficiency budget
Specific power is the sum of plant components. Improve the whole system, not only the chiller nameplate.
| Component | Typical kW/RT | Improved kW/RT |
|---|---|---|
| Chiller | 0.54 | 0.47 |
| CHWP | 0.04 | 0.04 |
| CWP | 0.04 | 0.04 |
| CT | 0.03 | 0.03 |
| Sys Eff | 0.65 | 0.58 |
Cooling load (RT)
RT ≈ [Flow × ΔT × constant] / 24
System efficiency = kW / RT. Site target on this platform is 0.58 kW/RT at 8.5°C supply condition, with ~0.65 kW/RT as a common norm band. Always label measured vs target and state the temperature condition.
Illustrative component budget redrawn from engineering practice. Not a guarantee for any site.
Measurement uncertainty
Temporary instrumentation is specified so total system uncertainty stays within accepted plant performance guidelines.
| Unit | Allowable uncertainty | Instrument |
|---|---|---|
| kW | 1.0% or better | Power meter with factory-certified CTs |
| Flow | 2.0% or better | Ultrasonic or magnetic flow meter |
| Temp | 0.5% or better | Thermistor with high-resolution instrument |
| Stability | 1.0% | Sustained reading stability under load |
Total system uncertainty ≈ ±5%
Per ASHRAE Guideline 22 practice and Singapore Green Mark plant efficiency measurement context. ΔT uses two temperature sensors. Site protocols may tighten these limits.
Where the kW/RT goes
Typical plant intensity includes design, commissioning gaps, controls, and maintenance. Optimised operation cuts the stack, not just one component.
Water side
Chillers + CHWPs + CWPs + CTs
kW/RT · design baseline ≈ 0.85 shown in stack body
Air side
AHUs + FCUs
kW/RT · design baseline ≈ 0.40 shown in stack body
Illustrative redraw from engineering practice (IDPM-style analysis). Percentages and levels are not a site guarantee. Align with measured plant data on each project.
Measurement products
Baseline Builder
Establish a defensible energy performance baseline.
SGD 249
Planning and baseline preparation
MRV Plan Generator
A structured measurement and verification plan.
SGD 295
Planning and baseline preparation
Chiller Performance Snapshot
Approximately seven days of temporary instrumentation.
SGD 1,950
Measured performance under real conditions
Negawatt Chiller Performance Study
Don't estimate performance. Measure it.
From SGD 4,950
Measured performance under real conditions
Performance Study + Opportunity Assessment
Measured performance plus optimisation priorities.
From SGD 5,950
Measured performance under real conditions
Measure + Optimise + Verify
Establish existing performance, improve it, measure again.
From SGD 9,950
Path toward verified conservation (not automatic NWT issuance)
Partner model
Methodology, not contracting sprawl
Negawatt Economy owns methodology, measurement specification, data standards, analytics, reporting, and Proof of Conservation methodology. Approved field partners undertake site installation and temporary metering.
Partner network →What we log
Cooling plant signals
- Chiller electrical power
- Chilled water flow
- Supply and return temperatures
- Cooling load and operating hours
- Ambient and condenser parameters where relevant
- Pump and tower energy where appropriate