HP1.3 · Integrated retrofit, economics and verification

Learning objectives

• Identify heat-exchanger, source, grid and legacy-backup dependencies.
• Separate energy cost, lifecycle cash flow and verified emissions boundaries.
• Design an evidence-based acceptance and monitoring plan.

Allow 30–45 minutes including derivations and exercises. All numerical values are teaching assumptions.

1. Map the retrofit around production

List the process users, operating modes, heat-source streams, distribution, electrical supply and existing boilers or chillers. Identify who controls each interface and which production condition is protected. Heat recovery can depend on another process whose schedule, contamination or shutdown may change independently of heat demand.

A retrofit may operate in hybrid mode with legacy equipment during transition or for contingency supply. State how the legacy path starts, its available capacity and fuel/utilities, and the permitted interruption. Retained equipment is a design input with maintenance and operating costs, not automatically a free or immediately available backup. [H1]

2. Coordinate electrical and thermal priorities

The EMS may see a price or network signal, while production requires heat at a minimum state. Define the protected heat inventory, electrical headroom and valid charging/discharging envelope before scheduling flexibility. The controls should have agreed rejection and fallback behaviour if a requested electrical action would breach the process limit.

Separate energy-management scheduling from equipment protection, pressure/temperature control and electrical protection. This course provides a functional boundary, not executable control or safety procedures. Responsible process and electrical specialists must establish interlocks, protection, commissioning methods and permitted operation for the actual installation.

3. Build one useful-service economic baseline

Compare alternatives for the same useful temperature, quantity, timing and reliability. The baseline may include fuel, boiler losses, electricity auxiliaries and maintenance. The new case may include electricity, demand charges, water/source handling, heat exchangers, storage losses, backup and production-change costs. Missing categories should remain visible rather than being silently set to zero.

The initial tool deliberately compares duty energy costs under stated prices. It does not infer annual savings, payback, financing or a discounted lifecycle result. A full business case needs representative time series, annual operation, installed quotations, replacements and consistent discount/tax assumptions, followed by sensitivity testing of the parameters that matter.

4. Measure claims with compatible meters and factors

To calculate an observed heating COP, measure useful heat and all included electrical energy over the same period and boundary. Identify whether pumps, fans, source preparation, defrost, standby or backup are included. A nameplate COP measured at one point should not be presented as a seasonal whole-system COP.

An emissions comparison also requires declared electricity and fuel factors appropriate to the location, time and accounting method. Electrification alone is not numerical evidence of a particular reduction. Keep energy and emissions results separate, disclose factor sources and avoid crediting both purchased certificates and the same physical saving twice.

5. Accept the integrated service and maintain it

Acceptance should test the useful process condition, the complete electrical/thermal boundary and agreed operating transitions, with suitable instrumentation and responsible specialists. Preserve initial conditions, installed configuration, time alignment, source conditions and deviations. Test results should map to the claim they actually support.

Monitoring then tracks useful delivery, temperatures, electricity/fuel inputs, source availability, storage state and maintenance. A changed production schedule, new electricity constraint or degraded exchanger can invalidate an earlier result. Assign owners and review triggers, including what evidence is needed before a revised flexibility service is allowed.

Worked answers and reasoning

Attempt the exercises before opening each answer.