Energy-Environment-Economics HVAC Systems acumen and Energy Management System (EMS) expertise allows us the ability to evaluate and critique past, present, and future design strategies. We believe that there are omnipresent instances of poor design practices, some even bordering on the ridiculous. Poor design, coupled with poor to marginal EMS application, system installation methods and non-existent project commissioning is, quite frankly, a recipe for our business.

In the case of complex system design, bigger most definitely does not mean better. This is even true for the most basic of system types, the packaged rooftop unit. Consider that an oversized packed unit will maintain temperature but will not run long enough for the cooling coil to reach the dew point and provide latent cooling. The result is high humidity levels and a potential breeding ground for molds and fungus. Whereas a properly sized unit will provide temperature and humidity control, costs less upfront to install and will reduce energy costs.

A large chilled water system is not immune from the bigger is better mentality of many engineers. Low hot/chilled water system temperature differentials (DT) are pervasive and counter-productive to proper operation and energy efficiency. Although generally misunderstood, low DT’s are a root cause of HVAC System inefficiency, as unnecessary equipment must be operated in order to compensate. Some system components are oversized, such as chilled water-cooling coils, leading to poor performance from possible laminar-turbulent flow fluctuations. A typical characteristic of all chilled water coils is that they will deliver approximately 80% of heat transfer capacity at 50% of the flow. An oversized or improperly circuited coil – or both as most are – will have a dramatic effect on space comfort and hot/chilled water system temperature differentials. Click here to read a detailed case study regarding the effects of low DT, how it was corrected and the resulting energy savings.

The causes of low system DT’s are many and complex, including improper central plant piping design, improper coil selection criteria, and control valve limitations. and identifying those causes takes expertise and experience, as does designing solutions that are minimally invasive and cost effective, and requires specific skills unfamiliar to most traditional engineering firms. But low DT’s are but one of countless reasons systems are inefficient, and our staff is extremely proficient in identifying said causes regardless of whether they be design, energy management or installation related.

In terms of comfort and energy efficiency, an HVAC system’s Air Distribution System is of equal importance to central plants. Fan motor horsepower (HP) is a significant contributor to energy consumption, and we commonly encounter air distribution systems that suffer from a variety of ailments including:

• Supplying quantities not required for comfort
• Supplying temperatures not required for comfort
• Supplying outside air quantities not required for proper IAQ
• Large variations in space pressures
• Improperly applied and controlled return air fans
• Underutilization of outside air economizer capabilities
• Poor duct design with excessive pressure drops

And of course air distribution system components such as coil selection criteria and control valve capabilities, as discussed above, have a major impact on the efficiency of the HVAC as a whole. To achieve true energy efficiency all of the sub-systems – air handling included – of the HVAC system must operate at the highest level possible for all assortment of inside and outside conditions.

Prime candidates for our HVAC Systems Optimization and Energy Conservation services would include:

• Constant flow (air and/or water) systems
• Low chilled water DT systems (operating at less than design, should be higher than design at system part load)) especially including existing primary- variable secondary flow systems
• Systems using return air fans, parallel or series fan-powered VAV boxes
• Any HVAC system with or without energy management (controls) capabilities
• Systems with apparently little or zero redundancy
• Systems with constant temperature and humidity deviations from setpoint
• Systems with inadequate or excessive outside air quantities, perhaps resulting in space pressure control issues
• Any system with excessive utility costs. What is excessive? If you are on this website your bills are probably excessive.