Analysis of Carbon Calculators

Fall 2007, 2008 graduate/undergraduate elective ‘Topics Studio’

Analysis of Carbon Calculators

Climate change is caused by an increase in the concentration of green house gas emissions due to human activities. Since buildings need energy to operate and be habitable, and this energy usually comes from power plants that generate CO2, buildings are responsible for a large portion of green house gas emissions. However, even though operation accounts for a major portion of building related greenhouse gas emissions it is not the only one.

The objectives of this exercise are a) to understand the variables that affect carbon emissions in buildings; b) to learn how to quantify these emissions; c) to compare different carbon counting tools or methods available for each task.

There are several types of carbon calculating tools: a) carbon footprint calculators which are available online to determine personal carbon emissions b) carbon estimators which are also available online for estimations of carbon emissions of buildings c) carbon calculators which are available for purchase that work with BIM systems for a more accurate analysis. In this studio, students focused on the first type of tools and some energy modeling programs.

Two single family dwellings were created as reference homes for later comparison with the student generated projects. Both of them were energy code compliant: a 1408 sq ft one-story house and a 2304 sq ft (gross building floor area) two-story house which was slightly smaller than the 2005 US avg. The houses had the following characteristics: the one story house was 32 by 44 ft and the two story house was 48 by 24 ft. Both were oriented east-west. Envelope to Glazing Ratio was 20% of the building distributed evenly in all elevations. U value of window in the coastal zone was 0.67 and inland was 0.55. SHGC = 0.40. The roof insulation was R30 with a radiant barrier in climate zone 9, and R30 in climate zone 7. If there was an option for water heater students used a gas storage water heater with a EF = 0.575.

Carbon emissions were determined for these houses in the two studio sites: climate zone 9 which includes Pasadena and Pomona with Hot and Dry Summers, and climate zone 7 which includes San Diego and Tijuana with a mild coastal climate (eg. Figs 2, 3). Carbon calculators were run for each of these homes and each team organized results in tables similar to Fig. 1. These tables included screen images of the tool (input and results page) and a short description of any assumptions made and comments on the tool. All tools were analyzed by at least two teams.

The values generated by the different tools were compared by the whole class to determine relationships and possible patterns (Fig. 4). Comparison was based on values that were generated by the tools, precision, speed, and ease of use.

At the end of the exercise a matrix was generated that included all of the tools that were analyzed and the areas in which they could be used.

• course outline

• project outline

Comparison of Carbon Calculators
Sarah Buck, Alan Thong, Serge Mayer, Lorenzo Medina, Derek Rungsea, Luis Torres, Luis A. Torres, Alexandra Hernandez, Aireen Batungbakal, Nicholas Klank, Naruki Nagata, Chuck Campanella, Kim Black, Megan Gorman, Kelly Saguini, Don Bui, Oscar Cobos, Michael Scott, Alexa Parks