High Performing Buildings - Spring 2008 - (Page 28)

C O M PA R I N G E N E R G Y M O D E L U S E T O AC T U A L E N E R G Y U S E By Commissioning Agent H. Jay Enck of Commissioning & Green Building Solutions, Inc. Reality is often different from assumptions made in energy modeling. In general, energy modeling has limitations, and comparing energy model results to actual energy recorded at the utility meter presents several obstacles. Assumptions were made for Sweetwater Creek State Park Visitor Center’s energy model regarding improved energy efficiency of demand based ventilation with CO2 concentrations to regulate the volume of outside air delivered over a given period. Variables include: • Daily population in the visitor center and time in a building; • Number of days represented by utility consumption for a given year (typically does not equal 365 days); and • Weather elements such as dry and wet bulb temperatures, enthalpy, clear sky percentages, precipitation, wind speed and direction. Typically, energy modeling programs use a variety of long-term average weather data files to estimate average energy consumption. Even with verified plug and equipment loads and schedules, weather files can create obstacles to accurate comparisons of calculated versus actual. For the visitor center, we used the original energy input file and actual weather data from the area. The closest weather station with the most complete data was Atlanta Hartsfield-Jackson International Airport, located 25 miles away. What we imagined as a relatively easy task was complicated by: • A plethora of weather file formats, each containing its own set of observational measurements, format and availability of reliable actual weather year data, expected data format versus indicated weather data format, and missing data; • Proximity of weather station to project site; and • A general lack of information or sparse and outdated information on alternative ways to accomplish actual weather year modeling. Sweetwater Creek State Park Visitor Center’s estimated annual energy consumption is 81,660 kWh. Using the actual dry and wet bulb temperatures in lieu of the historic averages raised the estimated energy consumption to 85,200 kWh. However, the actual energy use for 2006 was 94,680 kWh, 11% higher than estimated. Without measurements of actual occupancy, actual plug loads or contribution from the solar photovoltaic system for the same time period, it is difficult to determine the causes of the variance. Twin interior lightshelves below clerestory windows bounce daylight into the main exhibition space. that would be durable and easy to maintain; and materials that had minimal VOC off-gassing. Twelve percent of materials by cost, including photovoltaic solar panels recovered and reused from a gas station canopy, were salvaged. Additionally, 29% of the project’s materials by cost were manufactured within 500 miles of the project site. In response to the criteria listed earlier, primary exterior materials consist of masonry stucco, galvanized steel siding, preﬁnished steel roofs, vegetated roofs, and aluminum storefront and window systems. The provisions diverted 125 tons or 80% of the construction waste from landﬁlls. Financial Contributions Several ﬁnancial partnerships contributed to the success of this project. State funds represented less than 75% of the total project costs. The Friends of Sweetwater Creek State Park raised more than 28 HIGH PERFORMING BUILDINGS Spring 2008

Table of Contents for the Digital Edition of High Performing Buildings - Spring 2008

High Performing Buildings - Spring 2008
Daikin AC (Americas)
Contents
Seattle City Hall
SEMCO
3M Energy & Advanced Materials
Price
Sofame Technologies Inc.
Sweetwater Creek Visitor Center
ASHRAE Certification
Greenheck
Daylighting Strategies That Maximize Benefits
Energy Conservatory, The
ASHRAE e-learning
Ecobuild America
CTG Energetics, Inc.
Cambridge City Hall Annex
Tate Access Floors, Inc
Air-Conditioning, Heating, & Refrigeration Institute
31 Tannery Project
Building Owners & Managers Institute
Indian Springs Discovery Center
International Facility Management Association
ASHRAE Healthcare
Fulton Companies, The
AAON, Inc.

High Performing Buildings - Spring 2008