A Night at the Energy Modeling Improv

I recently attended a presentation on energy modeling. To my surprise, upon arrival one of the presenters was wearing a tall black pointed hat with a brim, and on the hat were gold crescent moons and stars – not a typical presenter at a lunch and learn seminar. The event was billed as “A Night at the Energy Modeling Improv”.

The “Wizard” (thus the hat) explained that we would be participating in an energy modeling exercise using the “Design Wizard” component the Quick Energy Simulation Tools software, more commonly referred to as “eQuest”. Energy modeling is an important component of building design, given today’s more stringent building codes. Energy modeling takes place during the schematic design phase of a project, and is an important tool in moving a building’s design forward. Energy modeling typically utilizes complex software, can be very time-consuming, and is generally thought of as being the bailiwick of the mechanical engineer. The eQuest software was developed by an engineer who wanted a quick, easy way to perform building modeling within several variables.

The Wizard explained we would be playing what they call “the Wizard Game”. He divided us into two groups. He gave us basic programming for the building including square feet and layout, number of stories, window information, R value of insulation for roof and for walls, and orientation. With the co-presenter operating the eQuest software for two different scenarios, our two teams competed against each other, with the software showing on a projection screen so we could see the results. Each team was given several choices of how to decrease energy usage. As each team made their selection of several variables, the co-presenter entered the data into eQuest so we could immediately see what, if any, energy savings was possible with our choices. Two choices stood out: one team chose to upgrade wall insulation, which didn’t cost much but also didn’t make much difference in energy savings. The other team chose to utilize daylighting, which increased electricity savings quite significantly.

That first game gave us a taste for the possibilities of choices that would help win the second game. For the second game, each team started by selecting a building footprint (out of 5-6 choices) and orientation (north-south or east-west). Other choices for the building envelope were square footage of window to wall ratio, glass type, sun shades, wall insulation, and roof insulation. Our team picked a better building footprint than the other team, but we stumbled a bit on glass selection, going for a low-E glazing. The Wizard explained that low-E really doesn’t do much for keeping heat out of a building in Texas, where we deal more with cooling than with heating (low-E works better in cold climates). We also could see what an important selection daylight harvesting is for providing energy savings for a building.

The eQuest Energy Wizard can be used by anyone, and is helpful in providing immediate feedback in modeling strategies during the design stage. This means energy modeling is no longer only something the mechanical engineer is involved in, but by using this simple, free software, anyone can obtain expertise in the concepts behind successfully modeling a given building. Just ask Mr. Wizard!

The eQuest software can be downloaded at www.doe2.com/equest and there is also a downloadable tutorial.

The DOE-2 software was developed by James J. Hirsch & Associates (JJH) in collaboration with Lawrence Berkeley National Laboratory (LBNL), with LBNL DOE-2 work performed mostly under funding from the United States Department of Energy (USDOE) and other work performed mostly under funding from a wide range of industry organizations, JJH and LBNL. The site, however, is not sponsored or endorsed by either USDOE or LBNL, and use of “DOE” in names in this site does not imply any endorsement or recommendation of any listed products or services by the United States Government, LBNL, or anyone else.

Daylight Harvesting

One of the intriguing and interesting ways to build sustainably is to use the practice of daylight harvesting or “daylighting” to light a building. As long as there have been windows, daylight has been used to light buildings, but in the era of (relatively inexpensive) electricity, good design practices went out the window, so to speak, and little attention was paid to this aspect of building design. Window placement was then determined based on what the designer was trying to do with the building’s façade, and in many cases, particularly in the 1980’s, it was fashionable to design buildings (particularly schools) without windows as it was considered to be “too distracting” to have windows. LEED has a credit for daylighting – IEQ credit 8.1.
Knowing what we know about human health, hormone production, circadian rhythms, and the various colors and intensities of daylight at different times of the year, one can assume that daylighting is important in human health, therefore in student learning.
Studies show some interesting benefits associated with the use of daylighting. Studies show students in daylit schools experience 3.2 to 3.8 fewer absent days. Studies also show students achieving higher test scores. Fewer dental caries and increased student growth are another correlation between daylighting and student health. In addition, students in daylit schools show better attention spans and better work habits. Schools also report teachers having fewer sick days when teaching in daylit schools. These are a few of the more well-known studies available on this high-performance building strategy.
Daylit buildings also offer substantial cost savings by reducing energy use. Since electrical lighting heats buildings, when lights are turned off cooling loads go down. Since commercial buildings use more cooling, on average, in the course of a year than heating (due in part to lighting, computer and human heat generation), turning off the lights realizes an immediate benefit for both lighting and mechanical systems. A second benefit is that of reduced electrical lighting, which will decrease utility bills. A third benefit of daylighting occurs when the use of HVAC is reduced; then HVAC noise is reduced. (Noise is a big issue in schools and is associated with difficulty in student learning.)
There is no one single successful strategy in the use of daylighting to achieve LEED credit 8.1. Windows should be strategically placed to provide light but not glare. Light should be bounced into areas further away from windows by the use of light shelves and/or reflective surfaces. Other methods are to use clerestory windows or skylights (skylights should be used with caution in areas prone to severe hailstorms). The use of sunshades will reduce glare while providing natural daylight. Interior lighting controls need to be used in order to maximize daylight harvesting. Use building modeling (LEED prerequisite) to determine an overall strategy for successful daylight harvesting. The use of daylight harvesting will create significant cost savings for the building owner and improved outcomes for students.

Student outcomes: http://www.nrel.gov/docs/fy00osti/28049.pdf
Pacific Gas and Electric Company (research conducted by the Heschong Mahone Group, Fair Oaks, CA), Daylighting in Schools: An Investigation into the Relationship Between Daylighting and Human and Performance, 1999.

Energy usage: http://www.lightnowblog.com/2009/01/study-captures-daylightings-hvac-and-lighting-energy-savings-impacts/

Daylight harvesting strategies: http://www.inive.org/members_area/medias/pdf/Inive%5CIBPSA%5CBS05_0501_508.pdf