- By Amy Milshtein
- August 1st, 2012
So much in life remains unpredictable, from the performance of your favorite sports teams to the stock market to your teen’s taste in music. From a planning and management perspective few things are worse than a building that consumes way more energy than expected. Energy modeling programs can take some of the mystery out of your building stock’s performance and help you meet LEED standards. Yet most schools don’t invest the time and resources into this technology. College Planning & Management offers a primer to help change that.
Energy modeling is not a new concept. “It’s been around in one form or another since the mid-1970s,” says Dr. Ellen Franconi, senior consultant, Built Environment Team, Rocky Mountain Institute. “Today modeling is moving beyond research into the private sector.” Franconi also remarks how well matched schools are to the technology. “Colleges and universities traditionally take a long-term view of their building stock,” she explains. “They are more demanding and savvy of the future performance than other owners, like that of a spec office building, for instance.”
Energy Modeling 101
In the Energy Modeling: A Guide for the Building Professional from the Colorado Governor’s Energy Office, energy modeling is described as, “the use of computer-based simulations to assess energy consumption, daylighting effects, and other characteristics of a building design. It allows for the analysis of various design considerations prior to the construction phase of a project. In this way energy modeling can help optimize alternatives and allow the design team to prioritize investment in the strategies that will have the greatest effect on the building’s energy use and occupant comfort.”
Energy modeling can be used to help a project achieve LEED standards, but it isn’t the only way to get LEED points. “You could also use ENERGY STAR products,” explains Dr. Dru Crawley, FASHRAE, director, Building Performance, Bentley Systems, Inc. “I see schools who want to achieve a LEED rating doing a 50/50 split with half going for ENERGY STAR products and the other half investing in energy modeling.”
While both systems lead to a more efficient building, using ENERGY STAR products compares your structure to other equivalent ones while energy modeling takes a detailed snapshot of the actual building. It can predict how that building will perform and allow users to make informed decisions on which mechanical and electrical systems to buy. “A robust energy model can weigh various design options in a way that other tools cannot, and it can supplement other decision criteria. Running a variety of models allows one to not only test feasibility, but to make informed cost-benefit analyses of various design options during any stage in the design process,” according to the Energy Modeling Guide.
Meeting Codes and Expectations
In some circumstances, modeling is the only way to go. “Places that have stringent energy requirements, like California, practically require energy modeling to meet the codes,” says Dr. Crawley. “For the rest of the country it really is LEED that is pushing the technology. Schools know that students care about LEED, so they are catering to their customers.”
“Campuses present a special opportunity when it comes to energy modeling,” continues Coreina Chan, consultant, building practice, Rocky Mountain Institute. “You have hundreds of buildings that complement each other in load, shape, and use. If you know what the buildings are consuming you can introduce simplicity to your central plant.”
With all of these advantages, the use of energy modeling is growing. With that growth comes some pains. Surprisingly, price isn’t one of the major issues. “Modeling is not that expensive, but energy costs are still low so some clients don’t want to invest in the technology,” says Dr. Crawley. While it is hard to put a dollar-per-square-foot number on the process, Dr. Franconi estimates that, “a small building might run $10-15,000 dollars to model while a larger, more complex structure could go as high as $75,000.” However, you get what you pay for. “The deeper you go with modeling, the bigger the potential savings,” she concludes.
In a building energy modeling innovation summit, Dr. Franconi outlined some problems with the field in an attempt to unite and energize practitioners. She points out a few issues in a pre-read paper to the summit: “To meet today’s market needs, the number of energy modeling practitioners has increased dramatically in a short period of time. These practitioners must follow complex modeling and reporting procedures, and very few have received formal training. Additional pressure is placed on the process since the modeling timeline is usually abbreviated, to coincide with the building design schedule.
“During the rapid growth of this industry, professional organizations, national labs, and even private consulting firms, have all made great contributions to the field of energy modeling. Despite these intentional (and often self-funded) efforts, there has been little collaboration amongst these various stakeholders, and many opportunities still exist to increase the effectiveness of modeling to support low-energy building design and operations.”
The Colorado report also points to an important issue. “Energy models are excellent tools for indicating relative changes in energy use comparisons between design options and of relative energy use. However, design phase energy models which are not calibrated with actual operating data do not predict absolute energy use during occupancy. Additionally, the energy model does not have the ability to accurately predict fluctuations in occupant behavior or utility costs. When compared to the energy model, atypical weather and changes to scheduled use are often the two largest drivers to a building’s performance.”
Dr. Crawley points to an example. “I had a friend who used energy modeling for a public library project he worked on. The original program called for the library to be open from 8:00 in the morning until 6:00 at night. When the client noted that the building was using much more energy than predicted, my friend came back and saw that the library was such a success that it was being used from 6:30 in the morning ‘til 10 at night. He recalibrated the numbers and the modeling matched the energy use.”
“You need the most robust modeling to effectively predict performance along with good data from the design team, user groups, and the owner,” agrees Dr. Franconi. “Then for the best results you should stick to the model mantra, ‘do it early and do it often.’”