Computer building energy simulations are an important tool in the design of low-energy buildings. Building energy modeling is used to predict annual energy consumption, determine peak loads for sizing equipment, complete cost-payback analysis to select appropriate energy efficiency measures, and show compliance with standards. While energy modeling is a cost effective tool to assist in design, there are a number of challenges in the current building energy modeling industry. Most energy modeling programs are too technical to be used by architects, and too complex for early design when many mechanical system parameters are not known. Programs that are easy to use lack accuracy and the ability to model new, innovative systems. Programs that allow the simulation of new systems are very complex and have a high learning curve.
A computer program to model building energy loads and energy consumption of mechanical systems has been developed. The program, titled “Building Energy and Loads Analysis” or BELA, has a transparent, open architecture to allow additions and changes, and facilitates the simulation of both simple early design and detailed later design. BELA is currently a simple, single-zone model but could be expanded in accuracy and in its range of capabilities.
This paper presents the theory and calculations used in the BELA program. To demonstrate the application of this program, a group of sample office buildings are modeled in both BELA and eQuest, a popular energy modeling program. The annual energy consumption calculated by each program for the sample group of buildings is compared, and it is seen that there is between 5% and 15% difference between the total energy consumption results of the BELA and eQuest programs.
This was presented at the 2011 Canadian Conference on Building Science and Technology.