Commercial applications are typically but not exclusively based on energy use in buildings. An office building may operate 3,500 hours per year compared to a refinery that operates continuously (8,760 hours per year). High and fairly constant thermal loads and a high number of operating hours per year characterise the commercial applications that are favourable to CHP. CHP systems are also typically sized to operate on a base load basis and utilise the electric grid for supplementary and backup power.
In recent years, the use of CHP in commercial buildings and multi-residential complexes has increased steadily. This is due largely to technical improvements and cost-reductions in smaller-scale, often pre-packaged, systems that match thermal and electrical requirements. Colleges and universities, government buildings, hospitals, offices, airports and health/sports centres represent almost 90% of installed CHP in the commercial sector, utilising gas turbines in the 1-10 MW range. Typical prime movers for this kind of CHP are reciprocating engines (spark ignition), Stirling engines, fuel cells and microturbines. These examples of commercial and institutional CHP users tend to have significant energy costs as a percentage of total operating costs, as well as balanced and constant electric and thermal loads (the temporal coincidence of heating / cooling demand with electricity demand can be particularly important for these applications).
Residential “micro” CHP technologies are also beginning to be developed and sold at the individual household level, and thus represent a potential mass market CHP product, provided that fully competitive and reliable products can be brought to market.