Waving the Wizard’s Wand of Energy Modeling

Wizard’s Wand of Energy Modeling

Since more and more builders and building owners are requiring minimum energy efficiency performance, more and more engineers are deciding they need to get on board by developing a better understanding of how to harness technology in advance of construction to ensure energy savings are achieved. It would be nice if they could look at an architect’s schematics and know intuitively the building will achieve desired energy performance levels. Unfortunately, engineers cannot predict the future. Fortunately, 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. They include 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. Lighting also influences energy consumption in several ways. The type and quantity of lighting, the building operation schedule, and the amount of natural lighting will factor into energy usage.

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 up several notches. In fact, twenty percent 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. The complexities of meeting energy performance standards are mind-boggling, and that is precisely why there are software programs to make success more probable.

Energy modeling requires a large volume of data. It is a fairly new field that 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. It is the interoperability of building properties that makes energy modeling something best left to software. Various strategies can be tested to determine their impact on energy usage. Want a cool roof, daylighting, natural ventilation, high R-value glazed windows? Input the data for one or all and see how energy performance changes.

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, and you will glad to know there are also excellent free building simulation software products available. 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.” There are no wands or pointy hats, but there are wizards of energy efficiency measures, schematic creation, and design development for building creation. These wizards produce graphical displays using a simulation program.

The energy modeling program will 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.

Are you intrigued? If so, there is a lot more to know, and you need to know it. Be sure to attend the Green Building Research Institute’s course on building energy modeling that begins August 27, 2014. The course will discuss energy modeling and eQuest in depth.

Have you ever used energy modeling software? If so, what lessons would you share with others just learning?

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