Life-Cycle Analysis of Building Retrofits at the Urban Scale—A Case Study in United Arab Emirates

Abstract

Abstract:A consensus is forming among experts that the best way to achieve emissions' reduction in the near and mid-term is increasing the demand-side energy efficiency-this is especially true in developing countries where the potential for demand reduction is significant and achievable at relatively lower cost. Enhanced energy efficiency also reduces energy costs and can result in a financial benefit to end-users, if the life-cycle value of energy savings offsets the upfront cost of implementing the measure. At the same time, reducing energy demand translates into lower pull for fossil fuel import and supply/distribution capacity expansion. An ideal candidate for the implementation of demand-side energy efficiency measures is the building sector, since it contributes to a large extent to the total amount of greenhouse gases (GHGs) emitted worldwide. In most developing countries, the contribution of the building sector to the total national GHG emissions is significantly higher than the worldwide average. This is in part due to the lower level of industrial activity. Other drivers of the high emissions of the building sector are the inefficiency of the envelope and technical systems of the existing buildings, as well as harsh climatic conditions requiring the use of energy intensive air-conditioning equipment. The United Arab Emirates (UAE) currently have the highest ecological footprint per capita in the world. The Emirate of Abu Dhabi, the focus of this study, can be expected to have a footprint that is even higher, being the largest economy and the major oil producer among the seven Emirates. In addition to the environmental consequences of unrestrained energy consumption, the fact that energy prices are heavily subsidized in OPEN ACCESSSustainability 2014, 6 454Abu Dhabi results in a significant financial burden for the government. In the UAE and the Emirate of Abu Dhabi, the air-conditioning load in buildings is the ideal target for demand-side management because it constitutes more than 60% of the total energy consumption. However, many sources of uncertainty still remain. How should we assess the life-cycle cost/benefit of candidate demand-side interventions? Which ones to choose in order to maximize national utility? This study will start to answer those questions by using a detailed engineering model of a typical Abu Dhabi building as specified by the Emirate's Urban Planning Council. Using the model building as a baseline, we then proceed to evaluate the energy impact of different retrofits through numerical simulation. We present a novel Marginal Abatement Cost Curve (MACC) for the Emirate of Abu Dhabi focusing exclusively on demand-side measures having an impact on the air-conditioning load. A surprising number of the abatement levers analyzed in this study exhibit a positive net present value (NPV), if the cost-reflective price of electricity is used for the life-cycle assessment.

Impact of Human Actions on Building Energy Performance: A Case Study in the United Arab Emirates (UAE)

“…Assuming an electricity tariff of 0.087 $/kWh, which is the unsubsidized cost of electricity generation in Abu Dhabi [32], the estimated savings in utility costs amount to $88.1 K/year, $18.5 K/year, and $8.4 K/year for the classroom, office, and dorm buildings, respectively. The results are in line with the work of Afshari et al [3], who varied HVAC set points for a commercial office building in the UAE. While the building type and experimental settings are different than the ones used in the current study, the authors in [3] estimated that a 4 • C increase in set point temperatures could lead to a reduction of 29% in cooling loads, which is equivalent to a change of 17.6% in the total building energy consumption.…”

“…The results are in line with the work of Afshari et al [3], who varied HVAC set points for a commercial office building in the UAE. While the building type and experimental settings are different than the ones used in the current study, the authors in [3] estimated that a 4 • C increase in set point temperatures could lead to a reduction of 29% in cooling loads, which is equivalent to a change of 17.6% in the total building energy consumption. The findings are very comparable to the ones observed in the current study, further confirming the validity of the results.…”

“…Given the academic nature of the facilities, which are typically open to students and/or staff around the clock, values of 24 • C are chosen to reflect more relaxed temperature values compared to occupied set points (i.e., 22 • C), while maintaining acceptable indoor conditions in case the space becomes occupied beyond regular working hours. Moreover, choosing unoccupied temperature settings that are close-or even similar-to those of occupied hours is common when modeling buildings in the UAE and other Arabian Gulf countries such as Kuwait [3,32,33], which further supports the choice of 24 • C as a set point for unoccupied periods. Next, the building energy models are run, generating energy intensity estimates (i.e., site electricity demand) of 257.1 kWh/m 2 /year for the typical office building, 195.1 kWh/m 2 /year for the classroom building, and 363.9 kWh/m 2 /year for the dorm building.…”

“…The values of all of the above-mentioned parameters are obtained from a variety of sources, including a report by the Abu Dhabi Urban Planning Council (UPC) [27], a study on the life-cycle analysis of building retrofits at the urban scale in the UAE [3], building standards [28], and other sources covering building benchmarking efforts [29,30]. A summary of the gathered data, which is later used as inputs to develop building energy models, is shown in Table 1.…”

“…Worldwide, this sector accounts for 30% to 40% of total energy consumption [2]. This ratio is even significantly higher in countries with extreme climate conditions such as the United Arab Emirates (UAE), where more than 70% of the power generated is consumed by buildings [3,4]. Over the life cycle of a typical building, more than 80% of the energy is consumed during the operation phase [5], while the remaining energy mainly goes to the construction and demolition phases.…”