Building Energy Software Tools
Formerly hosted by US Dept. of Energy    


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A versatile system design tool and an energy simulation tool in one package, Carrier's Hourly Analysis Program (HAP) provides the ease of use of a Windows-based graphical user interface and the computing power of modern 32-bit software.

 HAP's design module uses a system-based approach to HVAC load estimating. This approach tailors sizing procedures and results to the specific type of system being considered. Central AHUs, packaged rooftop units, split systems, fan coils, water source heat pumps and PTACs can easily be sized, as can CAV, VAV and multiple-zone systems. Calculation rigor and integrity are provided by the ASHRAE Transfer Function Method for calculating building heat flow.

 HAP's energy analysis module performs an hour-by-hour simulation of building loads and equipment operation for all 8,760 hours in a year. This approach provides superior accuracy versus the reduced hour-by-hour method used by other software programs on the market. This is because a full hour-by-hour calculation considers the unique weather and operating schedules for each day of the year, rather than looking only at average or typical days each month. Such accuracy is crucial when analyzing design alternatives, energy conservation methods and details of off-design and part-load performance for equipment. HAP uses TMY weather and the ASHRAE Transfer Function to calculate dynamic heat flow. Many types of air handling systems, packaged equipment and central plant equipment can be simulated.

Expertise Required: 

General knowledge of HVAC engineering principles and MS Windows software applications.


Practicing engineers involved in the design, specification and analysis of commercial HVAC systems/equipment. Instructional tool in colleges and universities. Design/build contractors, HVAC contractors, facility engineers, energy service consultants and other professionals involved in the design and analysis of commercial building HVAC systems. Useful for new design, retrofit and energy conservation work.


Building geometry, envelope construction, internal heat gains and their schedules; equipment components, configurations, controls and efficiencies; utility rates.


Over 50 design, and energy analysis reports and graphs document hourly, daily, monthly and annual energy and cost performance and are available to view or print. Design reports provide system sizing information, check figures, component loads and building temperatures. Simulation reports provide hourly, daily, monthly and annual performance data. All reports can be exported for use in word processors and spreadsheets. Energy costs can be calculated using complex utility rates which consider all of the common billing mechanisms for energy use, fuel use and demand.


HAP balances ease of use with technical sophistication. Technical features are comparable to DOE 2.1; comparison studies with DOE 2.1 have yielded good correlation. The Windows graphical user interface, report features, data management features, on-line help system and printed documentation combine to provide an efficient, easy to use tool. HAP can receive equipment performance data via electronic link from Carrier equipment selection tools.

United States
Major Capabilities: 
Whole Building Energy Simulation
Load Calculations
HVAC System Selection and Sizing
Building Type: 
whole building energy simulation
Last Software Update: 
30 June 2010
Last Entry Update: 
08 September 2018
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