Background Story

In multi-tenant buildings served by central cooling or heating plants, allocating energy costs fairly has always been a challenge. Traditionally, buildings rely on flat-rate billing or total building averages, offering no link between actual consumption and cost. This lack of visibility not only creates billing disputes but also hides operational inefficiencies — including those that contribute to Low Delta-T Syndrome.

BTU sub-metering changes this by measuring the exact thermal energy used by each apartment or space. This data empowers operators to pinpoint inefficiencies at the unit level, align tenant behavior with system performance goals, and create a fair and transparent billing system.


 

Problems
 

• No visibility into unit-level demand → operators can’t identify which tenants or zones are driving low Delta-T
• Chronic low Delta-T conditions from overcooling, faulty valves, or poor balancing go undetected
• Tenant disconnect from energy impact → flat billing encourages waste and excessive cooling
• Higher operating costs from increased pumping energy and reduced chiller efficiency
• Difficulty in targeting maintenance → without data, coil fouling or bypassing valves remain hidden until major performance drops occur

Main Objectives
 

• Improve transparency in energy consumption and cost allocation for all tenants

• Enable targeted diagnosis of low Delta-T causes at the apartment/zone level.

• Reduce chilled water flow and false loads on central plants

• Promote tenant engagement in energy-saving behaviors through direct accountability

• Support ongoing performance monitoring and verification for commissioning and retro-commissioning

Approach
 

• Install BTU sub-meters in each apartment or tenant space to measure both flow and temperature difference
• Integrate with BMS/EMIS to collect, as well as our Web-Based PBI Delta-T Management Analytics Tool to visualize ,and analyze real-time consumption and Delta-T trends
• Set automated alerts for zones with persistently low Delta-T or abnormal consumption patterns
• Use data for targeted maintenance — cleaning coils, recalibrating valves, or adjusting balancing in problem zones
• Educate tenants on their role in system efficiency, linking behavior changes to lower bills

Results
 

• Early detection and resolution of low Delta-T events before they spread building-wide
• Improved chiller and pump efficiency, reducing electricity costs and freeing up plant capacity
• Fair and transparent billing, eliminating disputes and aligning cost with actual usage
• Long-term performance assurance, with data-driven verification for system optimization projects