BioPCMTM reduces both peak cooling and heating design loads as well as reduces HVAC system run time. The reduction of peak design loads provides opportunity for designers to reduce capacities or in some cases entirely remove cooling and or heating systems. Reduced HVAC system run time reduces maintenance and extends system lifetime.
AHSRAE 90.1 Requires that building heating and cooling systems be designed to meet peak weather conditions, or 99.6% of the worst case heating hours and all but 1% of the worst case cooling hours. Further AHSRAE 90.1 recommends that cooling systems be sized at 15% above calculated cooling load, and heating systems at 20% above the heating load. This approach is to assure that in the case of extreme conditions the systems have a "safety factor". These strategies make sense and are best practices; however, it is noteworthy that HVAC systems do not run at these peak conditions most times of the year. Peak conditions are typically experienced less than 3% of the time, while "normal" conditions that the HVAC system runs under the majority of the time, only utilizes between 30% and 50% of the HVAC system capacity. HVAC systems partial load efficiency is crucial due to the industry standards that call for a system to be designed to safely meet peaks while providing conditioning for non peak conditions. BioPCM can provide an alternative path to these standard practices, especially when coupled with natural ventilation cooling and passive solar heating applications.
Downsize HVAC Equipment Capacities
Depending on the internal loads, orientation and controls strategy, bioPCM can reduce loads by sizable amounts. For example, a zone with bioPCM properly designed into it might have a 35% reduction in peak cooling load and a 26% reduction of peak heating load. An engineer could actually downsize equipment accordingly and still meet ASHRAE guidelines. By "right sizing" HVAC design based on the calculated loads with bioPCM, not only will a building owner save on energy operating costs, but also on the initial HVAC capitals costs.
Reduce HVAC Maintenance Costs
According to the ASHRAE owning and operating costs database, the average building HVAC maintenance cost is $0.50 per square foot. Considering that the average building spends $0.46 on HVAC energy per square foot annually, the cost of HVAC maintenance is on par with the cost of HVAC energy usage itself. BioPCM reduces HVAC run-time. This reduced HVAC system run time will not eliminate HVAC maintenance costs, but can reduce them significantly. As an initial estimate, it can be assumed that the reduction in HVAC maintenance costs will be directly proportional to the reduction of HVAC system run-time. For example, if a 68,000 square foot office building has an annual HVAC maintenance cost of $34,000 ($0.50/Square foot/Year) and bioPCM reduced HVAC run-time by an average of 23%, then the use of bioPCM would reduce annual HVAC maintenance costs by an estimated $7,800.
Extend HVAC System Lifetime
Central boilers, central chillers, heat & cool pumps, air distribution systems, pumps and controls systems equipment lifetimes typically last between 9 and 15 years with an average equipment lifetime of 12 years. Assuming a 23% average reduction of HVAC system run time and a proportional relationship to equipment lifetime, bioPCM can extend equipment life from 9-15 years to 11-18 years with an average of 15 years compared to the no bioPCM case average of 12 years.