Bringing Literacy into Broad Daylight4 Feb, 2008 By: Kenneth Wong
Energy analysis software helps usher light into the classroom.
When the Springfield Literacy Center in Pennsylvania is finished, the rowdy kindergarteners galloping in and out of the classrooms probably won't pay too much attention to the size of the windows or the volume of glazing on them. So long as the rooms remain well-lit throughout the day and the temperature within doesn't get unbearable during summer, they'll be satisfied.
But years later, should any of these youngsters take up architecture in college or university, they might have a greater appreciation for the thoughtfulness of the architects who designed their school environment. Burt Hill, Inc., the architecture firm responsible for the building, had to do quite a bit of number crunching to come up with the right configuration of windows, glazing, and light shelves to ensure the budding scholars' indoor comfort.
The sophisticated solar-thermal calculations and energy use predictions were made possible by two technologies: Autodesk Revit, a building information modeling (BIM) platform, and Integrated Environmental Solutions - Virtual Environment (IES-VE), a building performance modeling package.
Between 2006 and 2007, Burt Hill architects went back to school, in a manner of speaking. While developing ideas for the Springfield Literacy Center, they met with community members and Springfield School District's representatives. A number of those meetings were, in fact, held inside empty classrooms in local elementary schools ("The Springfield Literacy Center Educational Doctrine Report," January 18, 2007, Burt Hill).
From those meetings, the architects learned that the Facilities Committee was interested in long-term energy savings and, at a minimum, a LEED-certified rating from the U.S. Green Building Council.
Matthew Rooke, a LEED-accredited professional and a member of Burt Hill's performance analysis team, recalled, "We've been doing energy analysis even when we were primarily designing in 2D CAD, but we found that Revit and 3D BIM modeling in general threw open the doors for performance modeling. Because of the availability of a consistent 3D building model, we're now able to do more detailed analyses earlier in the design phase."
In 2003, Burt Hill began designing its projects in Autodesk Revit. Recently, IES-VE has emerged as one of the preferred energy analysis software packages for Revit users. For instance, with Revit MEP, a BIM package configured specifically for mechanical, electrical, and engineering works, the user can bring the Revit model directly into IES-VE.
For the Springfield Literacy Center, Burt Hill undertook three types of analysis:
- daylighting analysis, to understand shading and the effects of glazing
- shell analysis, to understand wall construction options
- natural ventilation analysis, to study the placements of openings
One of the site conditions that could potentially interfere with the energy performance of the building was the row of trees at the center. To preserve them, the architects split the 55,000-65,000 sq. ft. structure into two separate wings, increasing the depth that would be required to meet the program objectives.
|To accommodate the bank of trees cutting across the site of Springfield Literacy Center, the architects split the structure into two wings. (Click on image for a larger view.)|
During the design phase, a critical question was raised: How big should the windows be and where should be they be located (orientation and placement) for energy efficiency?
So Burt Hill's performance analysis team ran a daylight assessment on a classroom covering 669 sq. ft. For simulation, the team used the CIE Clear Sky model on March 21 at noon (a mathematical sky luminance model developed by the Commission Internationale de l'Eclairage), setting the working plane height at 30 inches and the desired illumination threshold at 25.000 footcandles.
The results showed that only 37.8% of the area in question was above the illumination threshold. For the LEED accreditation Burt Hill was targeting, 75% or more of the area must pass the correct threshold. It prompted the team to seek design alternatives to increase the light level.
"There's a tradeoff between daylighting and energy consumption," Rooke explained. "As you increase the window areas, the energy required to heat or cool the place increases. So we were balancing the daylight amount versus the [anticipated] annual energy cost to the owner."
Further analyses in IES-VE revealed the illumination inside could be increased by surface reflectivity, glazing, and light shelves.
|The tight integration between Autodesk Revit and IES-VE allows users to perform energy analysis with IES-VE tools directly from their Revit model.|
"A square foot of glass at the ground level is less helpful for daylighting than, say, if it were higher up in the window," Rooke pointed out. "So the daylighting analysis helped us find the optimum glazing placement to minimize solar heat gain and maximize daylight without introducing problems with glare. We also did shading studies to figure out the right size for the overhangs and light shelves to make sure the light level is just right for the students."
The analysis on the insulation values of various exterior wall options showed that an increased level of insulation in the wall (higher R-value) would improve the energy efficiency level.
Another energy saving feature was the use of energy recovery to precondition the ventilation air. "This was made even more critical because ventilation was increased in order to improve the indoor air quality, improving the learning environment and making the school a healthier place for children," Rooke explained.
|Burt Hill performed energy cost calculations to identify the anticipated annual energy costs of the Literacy Center.|
Better Early Than Late
"Traditionally, the architects would design the building, then send it off to a subcontractor or a consultant to do energy analysis," Rooke pointed out. "By then, the design has already been formalized, so there is a limit to how much you can change it."
The advantage of a product like IES-VE is that the architects can study the effects of their design instantly, make modifications, retest the design, and refine it over numerous iterations to achieve the desired energy efficiency level.
"Truly integrated design is essential for low energy and healthy buildings," Rooke concluded. "By bringing analytical data into the design process through building energy modeling, you can let performance drive the design, resulting in a holistically sustainable building."