D: Paper Session_T4: Retrofit Measures, Systems and Solutions
A Retrofit Scenario Analysis of Wall Systems Materials of a Low-Rise Commercial Building
Lawrence Technological University, United States of America
Low impact building materials have become key player towards achieving environmental sustainability in the built environment. Such materials also contribute to carbon neutral buildings, responding to AIA 2030 challenge and many other initiatives by governmental and professional institutions. Building enclosure incorporates many construction materials that contribute to overall embodied energy and environmental impact. It also affects building operational energy as a barrier between indoor and outdoor environment.
The study methodology performs an eco-balance inventory approach in calculating environmental impacts of exterior wall systems. The paper models an office building over a service life of 80 years and its implications on the environment from cradle to grave. It also quantifies and compares the total impacts of the enclosure systems of this building throughout this life span. The case study building is located in the Midwest in zone 5. The building skeleton is steel construction, columns and beams with multiple moment connections. This is the common method of construction for commercial buildings in this region. The building is a 3-story high that incorporates few sustainable features.
The study calculates the environmental impact of the building to air, water, and land. To achieve its goal, the study provides an assessment to which building enclosure component (walls, roofs) contribute the most to the total building impacts and identify the worst burden among its assembly systems. The outcome tests materials alternatives to use in the exterior wall system to minimize its impact. The paper employs a retrofit scenario analysis to evaluate replacing current high-impact materials with alternatives retrofit scenarios that have lower impacts and briefly calculate the reduction in the total building impacts against the original wall construction materials.
Cost-Effective Energy-Efficiency Retrofit Measures for Existing Buildings: Analysis for Reaching Net-Zero Energy Goals in Heating-Dominated Climate
University of Massachusetts Amherst, United States of America
Buildings consume 44% of the energy in the U.S. New construction buildings now have to abide by energy codes, however half of the U.S. buildings were constructed before 1980, when building energy standards where not as stringent. The annual replacement rate of existing buildings by new buildings is only around 1.0–3.0%. Meanwhile, commercial buildings account for 19% of the total energy used by buildings in the U.S. This study focuses on net-zero cost optimization of existing commercial office buildings in the U.S. The paper presents a methodology that was developed for optimizing net-zero energy commercial retrofit buildings using simulation-based optimization. The methodology was tested considering existing commercial buildings in a heating-dominated climate (Boston), where the
Commercial Buildings Energy Consumption Survey (CBECS) data was used to identify characteristics of typical buildings found in this climate. The multi-parameter optimization considered various energy-efficiency retrofit design measures, including building envelope retrofit, HVAC systems as well as various sources of renewable energy. The results identify the cost-optimal design solutions for five common building shapes in three different orientations. The study is expected to be a guide during conceptual design phase for designers and builders, and to help policy managers and energy efficiency program administrators in identifying future energy-efficiency measures and renewable energy technologies to achieve net-zero energy targets.
Assessment of Deep Façade Retrofit Solutions for Housing
University of Maryland, United States of America
Knowledge and research tying the environmental impact to operating energy efficiency improvement is a largely unexplored area in higher performance retrofit projects. It is a challenge to choose the façade renovation option that represents the optimal trade-offs among different performance objectives. This paper aims to test a multi-objective envelope optimization method to quantify and compare the deep retrofit façade techniques and their induced environmental impact. An integrated life cycle energy (LCE), life cycle assessment (LCA) and thermal comfort model (TCM) framework is proposed and used. Seven building façade retrofit options were studied to evaluate the operating energy saving, embodied energy increase and potential environmental impact. This project aims to better understand the pros and cons and trade-offs of different façade renovation options. The analysis results shows three findings: (a) the building construction method and the materials play equally important roles in the environmental impact; (b) the life cycle approach highlights the fact that energy saving alone is not sufficient when comparing different façade renovation technologies; and (c) for most renovation options, meeting thermal comfort requirements without mechanical cooling is more problematic than meeting them without heating. In addition, we noted that the tested integrated multi-objective optimization method can be applied to the renovation of other building systems, and the analysis results provide decision makers with the most comprehensive information.