The energy-saving properties of insulated concrete walls have permitted downsizing of heating, ventilation and air conditioning (HVAC) equipment by as
The energy-saving properties of insulated concrete walls have permitted downsizing of heating, ventilation and air conditioning (HVAC) equipment by as much as 15 to 40 percent in concrete homes as compared to identical wood-frame structures. To optimize the selection of correspondingly smaller, less expensive heating and air conditioning units, newly updated software published by the Portland Cement Association (PCA) allows builders to estimate heating and cooling system capacities for energy-efficient, single-family concrete homes and thereby maximize savings.
Developed as part of a HUD-sponsored project, the software calculates system capacities based on house dimensions, construction materials, air infiltration, location (U.S. Mexico, and Canada), and thermostat set point. To account for thermal mass imparted by concrete walls, the system uses hourly weather data for a typical year.
The PCA tool offers an alternative to widely used HVAC-sizing methods Û responsible for the installation of inefficient, typically oversized HVAC systems Û such as Manual J and the ASHRAE Load Calculation, which do not account for thermal mass, high levels of insulation, and/or low air infiltration of the insulated concrete walls, as well as builders’ and HVAC contractors’ rule-of-thumb, developed for wood-framed homes to size HVAC equipment by equating equipment size with square footage of living space. The updated software uses energy modeling that is more representative of actual conditions in which the HVAC system will be operating.
MS Excel version 97 or later is required for program operation. The software is available at www.cement.org/bookstore or 800/868-6733.