Carbon Emissions Based on Transportation for Post-Tensioned Slab Foundation Construction: A Production Home Building Study in the Greater Phoenix Arizona Area

Abstract

There is significant focus on sustainable development of the built environment. Previous studies on sustainable construction have focused primarily upon improving the energy efficiency of buildings during the operational phase, recycling/reuse of building materials, and minimizing wastes. The environmental performance of onsite construction processes is not currently measured or reported as an industry standard practice. Measurement of carbon emissions is one way to understand and improve the environmental performance of onsite construction processes. This study provides an estimation of carbon emissions for transportation in post-tensioned slab foundation construction. Data were collected from a concrete trade contractor and sub-trade contractors in the Greater Phoenix Arizona area. First, carbon emissions are quantified for a typical production home using regional average data. Second, the influence of material and equipment transportation on the relative contribution of trades toward total carbon emissions is quantified. Ready-mix concrete transportation is found to be one of the most significant components and accounts anywhere from 25% to 63% of the total carbon emissions. Third, what-if scenario analysis is presented to study the influence of floor slab size and the travel distance on carbon emissions based on ready-mix concrete supply. Finally, an example is presented to demonstrate the aggregate level impacts.

Keywords:

• carbon emissions
• onsite construction processes
• post-tensioned slab foundation construction
• production home building
• residential construction

Acknowledgment

This study was supported by Salt River Project (SRP) Grant CWU 0001 and Science Foundation of Arizona Grant CAA 009407. Data collection for this study was supported through a research grant award provided by Graduate and Professional Student Association of Arizona State University, Tempe, AZ. We would like to express our sincere gratitude to Mr. Steven Hay, Mr. Daniele Pagano, Mr. Ray Moyers and Mr. Artie Collins of SCP Construction, LLC who provided timely assistance and valuable feedback during data collection and site visits. Also, we would like to thank all sub-trade contractors who participated in this study. Review comments provided by the four anonymous reviewers and the journal editorial board are gratefully acknowledged.

Notes

Note. Fuel mileage represents average value based on fuel use record for one month.

Note. 1 Gallon Gasoline = 19.4 lb of CO₂; 1 Gallon Diesel = 22.23 lb of CO₂.

Note. X: Average one-way travel distance from the ready-mix concrete plant to the subdivision; Y: Average one-way travel distance from the concrete pump truck yard to the subdivision; Z: Average one-way travel distance from the ABC production plant to the subdivision.

Notes. ‘X’—One-way travel distance from the ready-mix concrete plant to the subdivision in miles; ‘Y’—One-way travel distance from the concrete pump truck yard to the subdivision in miles; ‘Z’—One-way travel distance from the ABC production plant to the subdivision in miles.

Metrics per subdivision is based on the assumption that there are 50 homes in the subdivision.

Metrics at the Greater Phoenix area level is based on the conservative assumption that 25,000 homes are completed per year.