Builders, engineers and design-build professionals face a common problem when it comes to choosing heating and cooling systems: how can they accurately compare different styles of HVAC systems, when they’re all tested to different standards and with various efficiency ratings? Now, a diverse group of commercial manufacturers has created a free tool that may help.
The group of manufacturers, supported by IAPMO and members of the Hydronics Industry Alliance (a Committee of the Radiant Professionals Alliance), has created a total commercial building HVAC system efficiency comparison tool that is now available online at no charge. The interactive Building Efficiency System Tool (BEST) was created to better inform prospective builders, consulting engineers and design-build professionals about their selection options for HVAC systems during the early design process.
The BEST uses the Building Energy Efficiency Ratio (BEER) – which looks at certified AHRI data, manufacturers’ published performance data at multiple performance points, as-applied correction factors, performance curves for components, and pipe and duct required in a typical system – and combines them to bridge the gap between certified equipment efficiencies and real-world building system efficiencies. For example, most direct-expansion equipment is laboratory tested at fixed points that include an 80°F room air temperature and 50% humidity (80 DB/67 WB). While a designer needs to know the rated performance to calculate system efficiency, BEST goes further by using the performance at actual operating temperatures (73 DB/61 WB) to develop an overall system efficiency, thereby more closely mirroring actual building operation.
Users simply enter the square footage of the building, the number of stories, and the nearest city for local weather data, and then choose up to four types of HVAC systems to compare – from more than 30 pre-loaded systems. The BEST features more than 100 default input settings, including system cost per square foot (provided by more than 50 contractors around the US), each of which are adjustable to model any building in any location. BEST then provides estimated installation cost, replacement cost, maintenance cost, monthly energy cost, electrical and fossil fuel consumption costs, total life cycle cost, cumulative life cycle cost by year, system payback time (as compared with other modeled systems), pump and fan HP, system integrated energy efficiency ratio (IEER), coefficient of performance (COP), and more.
To download the BEST tool, visit www.radiantpros.org.