Recipient Organization
UNIV OF MASSACHUSETTS
(N/A)
AMHERST,MA 01003
Performing Department
Environmental Conservation
Non Technical Summary
Sustainable design and construction strategies for the United States housing sector are the most economically effective strategy for preserving natural resources, reducing greenhouse gas emissions, and securing our energy future. In New England, more than 90% of the housing built are constructed from wood harvested from forests in New England and in the US, 55% of timber production goes into building construction. This McIntire-Stennis proposal focuses on investigating the environmental impacts and benefits of wood and other forest products used in residential construction in the northeast and developing strategies for optimizing lifecycle energy and environmental performance.Residential and commercial buildings in the United States use 70% of all electricity produced and account for nearly half of total energy consumption. Annual CO2 emissions linked to electricity consumption in U.S. buildings constitute about 39% of the country's annual total CO2 output. This does not include carbon emissions from manufacturing building materials and products. These impacts are projected to become more significant as building construction increases.A building has a lifecycle of 50-100 years or longer and building operations constitute approximately 80% of lifetime energy use and carbon emissions. Efforts are being made by builders, engineers, and architects to reduce the environmental impact of buildings, by designing and constructing high performance, low energy buildings. In the long term, as the impact of operations decreases (e.g. due to energy saving technology and changes in energy consumption behavior), the embodied energy, i.e. the energy consumed in the construction and demolition phases of the building's lifespan, will become increasingly significant. As buildings are optimized to consume less energy during operation, the net effect may be the use of more materials, and more energy and carbon-intensive materials, to achieve lower energy use. On the other hand, utilization of wood products can offset carbon emissions through long-term storage of carbon dioxide in the wood cells and fostering the use of more wood products may, in fact, result in lower carbon footprints. For example, double-stud walls are increasingly popular in high-performance residential construction. As the name implies this wall construction technique uses twice as much wood for framing as do traditional walls. Commonly filled with 30 cm of cellulose insulation this assembly contains and sequesters for the operational life of the building 80 kg m-3 of cellulosic material or about 35 kg C m-3.In light of this, our research proposes to use lifecycle analysis to explore the relationship between operational and embodied energy consumption and net carbon emissions over the full life-cycle of residential homes. By taking both embodied energy and embodied carbon into account, we will develop a new framework for quantifying the energy and carbon balance of residential buildings in New England. It is expected that this new framework will emphasize the environmental benefits of using wood and other forest products and may help to promote development of new wood products from New England forests. We will model typical single-family residential buildings compared to low energy residential designs (that use double-stud walls, for example) by local (Massachusetts-based) architects and builders. This study focuses on single-family houses, as this is a significant building growth trend in the US northeast. Moreover, it is among single-family housing owners that the sustainable design movement took root. As such, this is the market that has the greatest variety in terms of materiality, construction techniques, and innovative operations.The scientific contribution of our work will involve developing a framework to analyze the energy and carbon performance of wood-based construction materials over the projected lifetime of a residential building. We will define a method to quantitatively assess the carbon emissions and energy consumption associated with material production, construction, operation, maintenance, and disposal.Existing protocols for quantifying the performance of residential buildings do not systematically account for lifecycle energy consumption and carbon emissions. The proposed cradle-to-grave approach to quantifying the energy and carbon balance is a necessary first step towards defining environmental conservation strategies in the future. Furthermore, understanding the lifecycle performance of residential buildings will allow us to analyze the environmental impacts of green design strategies and green materials. The results of our analysis will help to improve measurement and verification methods for assessing New England residential structures, with the potential to impact green building codes and technology transfer in the forest products industry.
Animal Health Component
50%
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Goals / Objectives
The goal of this research is to illustrate a new way of quantifying environmental performance, by taking into account both the embodied and operational energy and carbon intensity and sequestration of the materials installed in wood construction residential buildings in New England. The research objectives are to evaluate and compare the lifecycle energy and carbon balance of single family wood framed homes in New England. This research will use buildings designed and built by local architects and builders as case studies. We will apply our analysis towards a baseline code-built home that has been continuously occupied for at least a year, a LEED certified home that has been occupied for at least a year, and a Net Zero Energy home design. The following tasks will be undertaken:1. Evaluate existing tools: Assess existing lifecycle analysis (LCA) tools (Athena Impact Estimator, NIST's BEES, and Pre's SIMAPro for residential assemblies) quantifying the energy and carbon intensities of selected case study residential buildings in New England.2. Develop and/or refine energy calculator for New England context: Account for the embodied energy (Lifecycle Energy - LCE) of building construction and material processing activities for select case study residential buildings.3. Develop and/or refine carbon calculator for New England context: Account for the embodied carbon (Lifecycle Carbon Equivalent - LCCE) and stored carbon of building construction and material processing activities for select case study residential buildings.Compare the operational (with DesignBuilder, which uses the Dept. of Energy simulation engine DOE 2.2) and embodied performance of case study buildings: Compare the life cycle operating and embodied energy and carbon intensities of various features in the case study buildings, in order to better understand possible trade-offs between the energy and carbon performance between material selection and operations.
Project Methods
The analytical methods of this research will build on the most complete and robust lifecycle database for North American construction, developed by the Canadian company, the Athena Institute. This analysis will be augmented by data from the National Institute of Standards and Technology (NIST) Engineering Lab's LCA tool, Building for Environmental and Economic Sustainability (BEES) and the international LCA standard, SimaPro 7. To accomplish each of the tasks outlined in section above, we will:1. Run simulations of three different case study homes (an existing code-built residential home in New England, a LEED home, and a Net Zero home) using existing LCA tools (eg. Impact Estimator, BEES and SimaPro). We will compare the results against alternate inventories and databases to assess the accuracy and relevance of the results. If the results are not comparable, this is most likely due to context and age - databases for building materials are sensitive to local building traditions, local supply chains, local resources, or may be out of date. We will conduct a lifecycle inventory analysis (LCI) to collect and update data on the inputs and outputs during each case study building's lifecycle. This will involve the following steps:a. Determine functional unit (what part or parts constitute the system) and boundaries of the analysisb. Creation of flow diagrams to show process flows with qualitative determination of inputs and outputsc. Inventory data collection involving mapping and quantifying how construction materials are extracted, manufactured, transported, assembled, and disposed.2. Using the Impact Estimator, BEES, and SimaPro LCA tools as the baseline, we will conduct a lifecycle impact assessment (LCIA) to translate the 'inputs' and 'outputs' of each process step for each case study building. Inputs will be quantified in terms of energy and resource use. Outputs will be quantified in terms of emissions and waste (e.g., global warming potential (GWP) as well as air emissions, solid waste disposal, waste water discharges).3. Using a similar approach to no. 2 (above) we will conduct an LCIA to quantify the carbon emissions for the 'inputs' and 'outputs' defined for each case study building.4. Data from no. 2 and 3 will be compared against operational energy and carbon impacts for each of the three case study buildings. Calculating operational energy and carbon impacts involves creating detailed models of the case study buildings using an established simulation program such as DesignBuilder (which uses the DOE 2.2 solution engine). The three case study buildings will be modeled using DesignBuilder to quantify yearly energy and carbon performance. It is important to note that these models focus only on the operations and maintenance phase of a building's lifespan. We will run test simulations to verify accuracy. Each case study building will have at least one year's worth of utility (energy and electricity) data from actual use. We will use the actual consumption data to fine-tune the computer model to within 2% accuracy. Then we will create a lifetime (50-100 years) operational energy and carbon impact assessment. Our model will incorporate scenarios for energy availability and changing climate factors in 50-100 years, to provide indicators of potential environmental impacts.The models will use the following data inputs:a. Location and context - includes meterological files (TMY weather files)b. Precise geometry and materials used for construction as well as their thermal properties and construction details (including air sealing strategies).c. Systems installed - all energy consuming equipment in the building, including heating, cooling, and ventilation systems as well as lighting and other peripherals.d. Schedules of use and occupancy, to account for behavioral and intermittent energy consumption patterns.This research is focused on the wood-based materials that are used for residential construction in New England. The data for the latter is currently insufficient in existing LCI databases and we will have to create the flow diagrams, input and output calculations, and criteria for evaluation. This is a non-trivial task and can present a roadblock in the process. However, our research team has strong ties to industry and manufacturing groups and will leverage these connections to develop a robust, contextually sensitive, and current lifecycle inventory for building materials in New England residences.