Chiller Plant Tender Specification: Capacity, Efficiency, Controls and Acceptance Tests

A chiller plant tender specification should fix five things: the design cooling load and redundancy, the rated efficiency as full-load COP and part-load IPLV at stated conditions, the plant configuration and controls, the refrigerant, and the acceptance tests with who witnesses them. Write the load and the test method into the document. Capacity and efficiency numbers that are not tied to a rating method cannot be compared or enforced.

What capacity basis goes into the specification?

State the design cooling load, how you derived it, and the diversity you allowed. Tender documents that say only "500 TR plant" invite bids on different assumptions. Give the load in kWr or TR, the chilled water supply and return temperatures, the ambient dry-bulb and wet-bulb design conditions, and the load profile across the year: hours at full, three-quarter, half and quarter load. Chillers spend most of their hours below full load, so the profile decides which machine is the better buy.

Say how much standby you require. The common choices are N+1, where one chiller is spare, and an arrangement of unequal machines so the plant can follow a low night load. Redundancy is a business decision about the cost of a cooling outage; our note on cooling redundancy shows how that is argued for critical loads. Use the chiller capacity calculator to check the load before you write it down. For the cost logic by efficiency class, see our guide to chiller plant cost drivers.

How do you write the efficiency clause?

COP is the full-load ratio of cooling output to electrical input. IPLV is a weighted figure for part-load operation. Ask for both, at the conditions you state, and tie them to a named rating standard. The Bureau of Energy Efficiency's Energy Conservation and Sustainable Building Code 2024 (ECSBC) requires chillers in covered buildings to be rated at full load and at part load in accordance with IS 16590, and ties the minimum efficiency to the BEE star rating of the chiller.

Two cautions on the table. First, ECSBC applies to commercial and office buildings with a connected load of 100 kW or more or a contract demand of 120 kVA or more, and whether it binds your project depends on whether your state or local authority has adopted it. It excludes equipment and parts of buildings that use energy for manufacturing processes. For an industrial process-cooling plant it is a reference to borrow from, not a requirement. Second, the plant energy figure in the last column is the code's alternate total-system threshold for chillers, chilled-water pumps, condenser-water pumps and cooling-tower fans together, so it tests the whole plant and not the chiller alone.

Whatever the building, make the tender ask bidders to declare COP, IPLV, the rating standard, the conditions and the tolerance, and evaluate on the energy the plant uses over your load profile, not the price of the machine. Our note on VFD retrofits shows what part-load control is worth.

How should the plant and its controls be specified?

The code's rules on plant configuration are a useful starting list. For ECSBC compliance it asks for water-cooled chillers where cooling water or recycled water is available. For buildings with a cooling load of 530 kWr or more it restricts air-cooled chillers to 33 percent of the installed chilled-water plant capacity, excluding standby, and lets the local authority require a higher air-cooled share. For Super ECSBC buildings with chilled-water systems above 1,500 kW cumulative or more than three chillers in one plant room, it requires controls that optimise chillers, pumps and cooling-tower fans against real-time demand.

Turn that into tender clauses:

• The chilled-water scheme: primary-secondary or variable primary flow, with the minimum flow the chillers allow.
• Pumps and tower fans on variable-speed drives, with the control variables named.
• A plant controller that stages chillers, resets set-points and logs kW per kWr, with open protocol points to the building management system.
• Instruments: flow meters, temperature sensors and power meters installed so the plant's efficiency can be measured after handover.

The plant-room side matters too: space for tube withdrawal, rigging routes, noise and vibration limits, and ventilation. Our guide to plant-room noise and vibration lists the checks.

What does the refrigerant clause need to say?

Name the refrigerant, or the allowed list, and ask for its ozone-depletion and global-warming potential and its safety class. The refrigerant market is moving. A Ministry of Environment, Forest and Climate Change memorandum of 1 April 2026 sets out India's Kigali schedule: a baseline built from 2024, 2025 and 2026, a freeze from 1 January 2028, and reductions of 10 percent by 2032, 20 percent by 2037, 30 percent by 2042 and 85 percent by 2047. The memorandum says the targets will be implemented through amendments to the Ozone Depleting Substances (Regulation and Control) Rules. Ask the bidder to state the refrigerant's service life support, leak detection, and recovery at end of life. Our note on A2L refrigerants and plant-room safety covers the safety side.

Which acceptance tests do you write in?

Specify tests, who performs them, who witnesses them, and what passes. The ECSBC commissioning appendix is a process model: an owner's project requirements document, a commissioning plan with construction checklists, test procedures for each system, and clear responsibility for who performs and who approves each test. Apply it to a chiller plant as follows.

Tie a part of the payment to the performance test, and say what remedy applies if the plant misses its declared figures. Our glossary entry on HVAC commissioning and our testing and commissioning page set out the activities.

How Secured Engineers helps

We design chilled-water plants in-house with the electrical, plumbing and fire design, so the plant room, the power feed, the make-up water and the fire protection are coordinated before tender. We file Fire NOC, CEIG and DISCOM applications in-house and deliver MEPF and solar under one contract. We work from offices in Noida (Delhi NCR) and Ludhiana, with 535+ projects across 18+ states and 89.77% repeat clients.

Send us your draft specification, the load calculation and the bids you have received, and we will review them against each other and tell you what is missing or not comparable. See our chiller plant page, message us on WhatsApp, call +91 70099 85817, or ask for a free proposal.