Worked example
What your assessment report looks like
Every NetZero Global net-zero performance assessment produces a full report: the EN 15232 efficiency class today and after upgrade, projected energy and cost savings, CO2 reduction, payback, NPV and a year-by-year cashflow. Below is a complete worked example for a offices retrofit — the real thing, generated by our assessment engine.
Net-Zero performance assessment
Acme HQ — Office Retrofit (Sample)
Acme Real Estate Holdings Ltd · Offices · 8,200 m² · London, UK
1 · Executive summary
Current class
Planned class
Method
Annual energy savings
Annual cost savings (yr 1)
Annual CO₂ reduction
Simple payback
Discounted payback
Net present value
Internal rate of return
Investment
Useful life
2 · Project information
| Project name | Acme HQ — Office Retrofit (Sample) |
| Project ID | SAMPLE-001 |
| Date | 2026-06-01 |
| Customer | Acme Real Estate Holdings Ltd |
| Contact | noor.haddad@acme.example |
| Engineer / assessor | NZG Sample Engineer |
| Location | London, UK |
| Assessment method | EN 15232:2012 (standard factors) |
Scope & notes
Demonstration scenario — illustrative numbers, not a real assessment. Existing installation is a legacy class-C BACS. Planned upgrade brings the building to class A with full TBM, presence-based controls, daylight harvesting and HRV efficiency control.
3 · Building
| Type | Offices |
| Description | Open-plan or cellular office buildings with mixed occupancy schedules. |
| Floor area | 8,200 m² |
| Typical thermal demand (this building type) | 110 kWh/m²·a |
| Typical electrical demand (this building type) | 70 kWh/m²·a |
| Thermal split | 65 % heating · 5 % DHW · 30 % cooling |
Weighting factors for Offices
| Class | Thermal fth | Electrical fel |
|---|---|---|
| A · High energy performance | 0.70 | 0.87 |
| B · Advanced | 0.80 | 0.93 |
| C · Standard | 1.00 | 1.00 |
| D · Non-energy-efficient | 1.51 | 1.10 |
4 · Plants in scope
6 of 7 plants are active in this assessment.
| Heating | In scope |
| Hot water (DHW) | Excluded |
| Cooling | In scope |
| Ventilation & HVAC | In scope |
| Lighting | In scope |
| Blinds & sun shading | In scope |
| Building management | In scope |
5 · BACS function selections
| Plant | Category | Function | Current | Planned |
|---|---|---|---|---|
| Heating | Room-level heat output | Room-by-room heat control | C | A |
| Heating | Hot-water distribution | Circulation pump | C | A |
| Heating | Hot-water distribution | Supply-water temperature | C | A |
| Heating | Hot-water distribution | Setback when empty | C | A |
| Heating | Heat generation | Boiler / district-heat regulation | C | A |
| Heating | Heat generation | Heat-pump regulation | C | A |
| Heating | Heat generation | Choosing between multiple heat sources | C | A |
| Cooling | Room-level cooling | Room-by-room cooling control | C | A |
| Cooling | Chilled-water distribution | Chilled-water pump | C | A |
| Cooling | Chilled-water distribution | Off-hours cooling | C | A |
| Cooling | Coordination with heating | Prevent simultaneous heating and cooling | C | A |
| Cooling | Chiller plant | Chiller water-temperature regulation | C | A |
| Cooling | Chiller plant | Free cooling from outside air or water | C | A |
| Ventilation & HVAC | Room-level airflow | How airflow is set in each room | C | A |
| Ventilation & HVAC | Whole-plant airflow | Air-handling unit (AHU) fan control | C | A |
| Ventilation & HVAC | Heat recovery | Heat-recovery exchanger management | C | A |
| Ventilation & HVAC | Free mechanical cooling | Night and free-air cooling | C | A |
| Ventilation & HVAC | Supply air temperature | Supply-air temperature control | C | A |
| Ventilation & HVAC | Humidity | Humidity control | C | A |
| Lighting | Switching by occupancy | How lights respond to people | C | A |
| Lighting | Daylight harvesting | How daylight is used | C | A |
| Lighting | Scenes & dimming | Scene presets and dimming | C | A |
| Blinds & sun shading | Sun-shading control | How blinds are operated | C | A |
| Blinds & sun shading | Glare and solar gain | Glare and solar-heat management | C | A |
| Building management | Central monitoring | Set-point management and oversight | C | A |
| Building management | Fault detection | Fault detection and diagnostics | C | A |
| Building management | Energy reporting | Energy metering and reporting | C | A |
| Building management | Optimisation | Demand-side supervisory optimisation | C | A |
| Building management | Occupant interface | Occupant feedback and overrides | C | A |
6 · Energy baseline
| Stream | Consumption (kWh/yr) | Source | Price (£/kWh) | CO₂ (kg/kWh) | Cost (£/yr) |
|---|---|---|---|---|---|
| Heating | 586,300 | Natural gas | 0.075 | 0.202 | 43,973 |
| DHW | 45,100 | Natural gas | 0.075 | 0.202 | 3,383 |
| Cooling | 270,600 | Grid electricity | 0.285 | 0.193 | 77,121 |
| Electrical | 574,000 | Grid electricity | 0.285 | 0.193 | 163,590 |
7 · Financial assumptions
| Investment (£) | £145,000 |
| Annual O&M delta (£/yr) | -£2,500 (saving) |
| Energy-price escalation | 3% / year |
| Discount rate | 5% |
| Useful life | 15 years |
8 · Per-plant savings breakdown
| Plant | Energy saved (kWh/yr) | Cost saved (£/yr) | CO₂ saved (kg/yr) |
|---|---|---|---|
| Heating | 175,890 | 13,192 | 35,530 |
| Cooling | 81,180 | 23,136 | 15,668 |
| Ventilation & HVAC | 7,855 | 2,239 | 1,516 |
| Lighting | 35,346 | 10,074 | 6,822 |
| Blinds & sun shading | 3,927 | 1,119 | 758 |
| Building management | 27,492 | 7,835 | 5,306 |
| Total | 345,220 | 58,610 | 68,332 |
9 · Year-by-year cashflow
| Year | Annual cashflow (£) | Cumulative (£) | Cumulative discounted (£) |
|---|---|---|---|
| 0 | -145,000 | -145,000 | -145,000 |
| 1 | 61,110 | -83,891 | -86,800 |
| 2 | 62,943 | -20,948 | -29,710 |
| 3 | 64,831 | 43,883 | 26,294 |
| 4 | 66,776 | 110,659 | 81,231 |
| 5 | 68,779 | 179,439 | 135,121 |
| 6 | 70,843 | 250,281 | 187,985 |
| 7 | 72,968 | 323,249 | 239,842 |
| 8 | 75,157 | 398,406 | 290,711 |
| 9 | 77,412 | 475,818 | 340,611 |
| 10 | 79,734 | 555,552 | 389,561 |
| 11 | 82,126 | 637,678 | 437,579 |
| 12 | 84,590 | 722,268 | 484,681 |
| 13 | 87,128 | 809,395 | 530,887 |
| 14 | 89,741 | 899,137 | 576,212 |
| 15 | 92,434 | 991,570 | 620,675 |
10 · Disclaimer
This report is an indicative aid, not a certified energy-performance assessment.
The numerical weighting factors used are derived from publicly described values associated with EN 15232:2012, the European standard Energy performance of buildings — Impact of Building Automation, Controls and Building Management. EN 15232 is © CEN. Users requiring a binding classification must consult the published standard directly and engage a qualified assessor.
The "NZG weighting" alternative is a tool-specific heuristic invented for this software and does not represent any third-party methodology.
Financial figures (NPV, IRR, payback) follow standard discounted-cashflow practice and do not account for tax, depreciation, subsidies, fuel-specific escalation or grid decarbonisation.
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