https://doi.org/10.24928/2023/0128

Defining CO2 Emissions of a Construction Project on the Basis of Programmatic Information

Ari Pennanen¹, Saku Metsärinne² & Pyry Haahtela³

Abstract

The environmental impact that a product has over its subsequent life is largely determined by decisions taken during the delivery process, i.e. defining needs for the product, choice of geometry, and choice of materials (Ashby W.R). Ashby’s description is universal, covering all kinds of products. But if we make an interpretation to construction, environmental impact is due to 1) programming process (needs for the product), 2) massing during preliminary design (choice of geometry), and 3) choice of materials during detailed design. At the moment, CO2 emissions are mostly defined from the use of materials during detailed design and construction, and from life cycle consumptions based on detailed design. In the detailed design stage, quantities of materials can be measured. And, as the mass of the building, internal conditions (e.g. internal climate) and external conditions (e.g. climate) are known, life cycle emissions can be modeled (or actually, calculated). The problem is that this kind of approach does not involve a project definition or early massing during preliminary design to challenge designers to consider CO2 emissions as they steer early design forward. However, the most important decisions in relation to environmental impact are done during programming and massing in the preliminary design stage. If we set a question whether we need an auditorium or not, the decision made affects vastly more than latter decisions of the materials of the supposed auditorium. The need for an auditorium is not a design problem, rather it is a functional (i.e. programming) problem. And onwards, massing during preliminary design dictates the quantities of the materials measured later (more or less efficient massing, corridors, compact or scattered, more or fewer floors, etc). Longer distances between customer functions affect the quantities of staircases, external wall, air exchange ducts, cabling and site processes during construction in site (Pennanen, Ballard, Haahtela). The authors argue herein that life cycle analysis (LCA) calculations should be used to help customers set goals, i.e., LCA should be used to steer design. Similarly, LCA should steer contractors and designers in detailed design. If CO2 emissions are defined only from material quantities of detailed design, analysis is then rather declarative than helping to steer the design, as the calculation happens after the last responsible moment for programming and material selection. This paper presents a theory and applications to involve the client and early design to proactive steering of CO2 emissions during programming and early design; allowing all partto collaboratively determine what CO2 emission goals to set for a project as well as how best to achieve those goals.

Keywords

Lean and green. Product development, value and design management.

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Reference

Pennanen, A. , Metsärinne, S. & Haahtela, P. 2023. Defining CO2 Emissions of a Construction Project on the Basis of Programmatic Information, Proceedings of the 31st Annual Conference of the International Group for Lean Construction (IGLC31) , 454-461. doi.org/10.24928/2023/0128

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