Phoenix's first net-zero energy office retrofit: A green and lean case study

Akash Ladhad, Kristen Parrish

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Many in the construction industry view lean practices as a means for reducing cost and schedule while maintaining or improving quality. This paper argues that lean practices can also be used to promote energy savings throughout a building's life cycle. This paper presents a case study of an existing building retrofit in Phoenix, Arizona. The project owner, a general contractor, self-performed much of the building construction and worked to ensure the project team aligned around the project's net-zero energy goal. All building systems, excepting the walls and roof, were re-designed and re-constructed. After retrofit, the building has achieved net-zero energy consumption; that is, the building produces as much energy as it consumes on an annual basis. Deep building energy retrofits typically result in larger energy savings than operational changes alone can provide, as these retrofits take a whole-building approach to design (i.e., optimize the whole) and implement integrated project delivery methods (e.g., (AIA, 2007)). This paper discusses a net-zero energy retrofit and how lessons learned on this project could apply to other deep energy retrofits for commercial buildings (where "deep" refers to energy savings of 25% or more) that may significantly improve building value (Miller and Pogue, 2009). The inefficiency of existing building stock supports the need for retrofitting: energy consumption in the existing building stock in the United States accounts for approximately 41% of the total primary energy consumption (US DOE, 2012). In order to reduce this consumption, existing buildings must be retrofit, through replacement or upgrade of their existing building systems, to improve their energy performance. Beyond the energy motivation, a building's operating costs account for the largest portion of the life cycle cost. Thus, deep energy retrofit projects offer an opportunity to significantly reduce both national energy consumption and expenditures. While much research exists on the topic of energy retrofits, very little explores the role of the contractor. This paper explores the contractor's role (rather than the designer's or engineer's role) in delivering deep energy retrofit projects. The contractor plays a critical role in delivering a project that meets the owner's expectations and goals and satisfies the specifications (Ahn and Pearce, 2007). Namely, the contractor executes the plans and specifications, giving physical reality to the design team's vision. In the case of deep energy retrofits, this role is particularly important, as installation and operation must conform to the design intent to achieve the predicted energy performance. Moreover, the contractor must understand the existing condition to effectively retrofit the building. This paper explores critical building energy efficiency measures and processes for achieving deep energy savings in retrofit projects. Specifically, we present the role of the contractor in a case study project in Phoenix, Arizona where the contractor was engaged in the project early in the design stage. This paper discusses the process of developing and selecting energy efficiency measures (EEMs). It explains the reasons for choosing particular EEMs, including a discussion of selecting an appropriate baseline for energy savings calculations, and documents the impact of EEMs on total energy consumption and design intent. The paper concludes with a discussion of recommendations that, if applied in part or whole, will increase the effectiveness of future construction teams in delivering deep energy retrofit projects.

Original languageEnglish (US)
Pages (from-to)3-16
Number of pages14
JournalJournal of Green Building
Issue number4
StatePublished - 2013


  • Collaboration
  • Deep energy savings
  • Energy efficiency measures
  • Integration
  • Lean construction
  • Net-zero energy
  • Process
  • Retrofitting
  • Work structure

ASJC Scopus subject areas

  • Environmental Engineering
  • Geography, Planning and Development
  • Civil and Structural Engineering
  • Architecture
  • Building and Construction
  • General Environmental Science
  • Public Health, Environmental and Occupational Health
  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law


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