Since an increasing number of builders and building owners are requiring minimum energy efficiency performance, more engineers are deciding they need to get on board by developing a better understanding of how to harness technology prior to construction to ensure energy savings are achieved. It would be nice if they could know intuitively the building will achieve desired energy performance levels just by looking at the architect’s schematics. Unfortunately, engineers cannot predict the future, but they can certainly model it.
Energy modeling software enables engineers to simulate building energy performance. Whole building energy simulation considers all factors that influence energy consumption such as interior and exterior lighting, service hot water, equipment power density, receptacle loads, HVAC systems, building envelope, planned use and occupancy, local climate and a lot more. Each one of these factors has numerous components. For example, the building envelope includes walls, windows, floor and roof. HVAC includes the type of heating and cooling, energy source, ventilation type and planned scheduled use. Several lighting factors also affect energy usage such as the type and quantity of lighting, the building operation schedule and the amount of natural lighting.
Evolving to Higher Degrees of Accuracy
Though energy modeling is not a new concept, it should be viewed with fresh eyes. The new LEED v4 takes optimizing energy performance to the next level. In fact, 20% of LEED v4 points are related to energy performance in the context of the building lifecycle. LEED v4 adopts new ASHRAE standards for carbon reduction and the production of energy by the building system. Meeting energy performance standards can be very complex, which is why there are software programs to make success more probable.
Energy modeling requires a large volume of data and is evolving to incorporate a growing body of knowledge. It is most effective when used during the conceptual stage of building design so that important changes can be made as needed. The model requires inputting building information that flows to energy analysis. Measuring the energy usage of variables such as using a cool roof, daylighting, natural ventilation or high R-value glazed windows is all made possible with just a few clicks. Hence, it is the interoperability of building properties that makes energy modeling something best left to software.
Free is Always Good
Since energy performance cannot be calculated with paper and a calculator, the first step is choosing a good software program. Plenty are available including some excellent free building simulation software programs. One of the popular freeware building energy use analysis software programs is eQuest, a DOE-2 product developed by James J. Hirsch & Associates in collaboration with the Lawrence Berkeley National Laboratory. Funded mostly by the Department of Energy, eQuest is a sophisticated simulation tool that was developed with ease of use in mind. It performs detailed comparative analysis by using wizards for energy efficiency measures, schematic creation, and design development for building creation. These wizards produce graphical displays using a simulation program.
Energy modeling programs such as eQuest help architects and engineers determine building features that meet ASHRAE standards and optimize performance. The eQuest program also contributes to the life cycle approach that LEED v4 takes to new heights. It does loads analysis, plant analysis, systems analysis and economic analysis. Of course, the proposed building needs something to be compared against which is why the same computer simulations program will calculate a baseline. As an evolving tool in terms of technology, there is enormous opportunity for people in the field to help the software creators refine their programs to reflect real-world experiences.
Have you ever used energy modeling software? If so, what lessons would you share with others just learning?