Optimization of cool roof and night ventilation in office buildings: A case study in Xiamen, China

Increasing roof albedo (using a “cool” roof) and night ventilation are passive cooling technologies that can reduce the cooling loads in buildings, but existing studies have not comprehensively explored the potential benefits of integrating these two technologies. This study combines an experiment in the summer and transition seasons with an annual simulation so as to evaluate the thermal performance, energy savings and thermal comfort improvement that could be obtained by coupling a cool roof with night ventilation. A holistic approach integrating sensitivity analysis and multi-objective optimization is developed to explore key design parameters (roof albedo, night ventilation air change rate, roof insulation level and internal thermal mass level) and optimal design options for the combined application of the cool roof and night ventilation. The proposed approach is validated and demonstrated through studies on a six-storey office building in Xiamen, a cooling-dominated city in southeast China. Simulations show that combining a cool roof with night ventilation can significantly decrease the annual cooling energy consumption by 27% compared to using a black roof without night ventilation and by 13% compared to using a cool roof without night ventilation. Roof albedo is the most influential parameter for both building energy performance and indoor thermal comfort. Optimal use of the cool roof and night ventilation can reduce the annual cooling energy use by 28% during occupied hours when air-conditioners are on and reduce the uncomfortable time slightly during occupied hours when air-conditioners are off

Energy Retrofit in European Building Portfolios: A Review of Five Key Aspects

The research about energy efficiency in buildings has exponentially increased during the last few years. Nevertheless, both research and practice still cannot rely on complete methodologies tailored for building portfolios as a whole, because the attention has always been drawn to individual premises. Yet, energy efficiency analyses need to go beyond the single building perspective and incorporate strategic district approaches to optimize the retrofit investment. For this purpose, several aspects should be considered simultaneously, and new methodologies should also be promoted. Therefore, this paper aims to discuss energy retrofit campaigns in building portfolios, drawing an exhaustive and updated review about the challenge of jumping from the single-building perspective to a stock-based analysis. This research discusses the publications available on the topic from five key aspects that are all essential steps in achieving a complete and reliable study of energy efficiency at a portfolio level. They are energy modelling and assessment, energy retrofit design, decision-making criteria assessment, optimal allocation of (financial) resources and risk valuation. This review, therefore, advocates for joint consideration of the problem as a basis on which to structure further disciplinary developments. Research gaps are highlighted, and new directions for future research are suggested

Energy performance forecasting of residential buildings using fuzzy approaches

The energy consumption used for domestic purposes in Europe is, to a considerable extent, due to heating and cooling. This energy is produced mostly by burning fossil fuels, which has a high negative environmental impact. The characteristics of a building are an important factor to determine the necessities of heating and cooling loads. Therefore, the study of the relevant characteristics of the buildings, regarding the heating and cooling needed to maintain comfortable indoor air conditions, could be very useful in order to design and construct energy-efficient buildings. In previous studies, different machine-learning approaches have been used to predict heating and cooling loads from the set of variables: relative compactness, surface area, wall area, roof area, overall height, orientation, glazing area and glazing area distribution. However, none of these methods are based on fuzzy logic. In this research, we study two fuzzy logic approaches, i.e., fuzzy inductive reasoning (FIR) and adaptive neuro fuzzy inference system (ANFIS), to deal with the same problem. Fuzzy approaches obtain very good results, outperforming all the methods described in previous studies except one. In this work, we also study the feature selection process of FIR methodology as a pre-processing tool to select the more relevant variables before the use of any predictive modelling methodology. It is proven that FIR feature selection provides interesting insights into the main building variables causally related to heating and cooling loads. This allows better decision making and design strategies, since accurate cooling and heating load estimations and correct identification of parameters that affect building energy demands are of high importance to optimize building designs and equipment specifications.Peer ReviewedPostprint (published version

Cost-effective analysis for selecting energy efficiency measures for refurbishment of residential buildings in Catalonia

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/This paper presents the results of a detailed method for developing cost-optimal studies for the energy refurbishment of residential buildings. The method takes part of an innovative approach: two-step evaluation considering thermal comfort, energy and economic criteria. The first step, the passive evaluation, was presented previously [1] and the results are used to develop the active evaluation, which is the focus of this paper. The active evaluation develops a cost-optimal analysis to compare a set of passive and active measures for the refurbishment of residential buildings. The cost-optimal methodology follows the European Directives and analysed the measures from the point of view of non-renewable primary energy consumption and the global costs over 30 years. The energy uses included in the study are heating, domestic hot water, cooling, lighting and appliances. In addition, the results have been represented following the energy labelling scale. The paper shows the results of a multi-family building built in the years 1990–2007 and located in Barcelona with two configurations: with natural ventilation and without natural ventilation. The method provides technical and economic information about the energy efficiency measures, with the objective to support the decision process.Postprint (author's final draft

Life-cycle assessment of buildings: a Review

Life-Cycle Assessment (LCA) is one of various management tools for evaluating environmental concerns. This paper reviews LCA from a buildings perspective. It highlights the need for its use within the building sector, and the importance of LCA as a decision making support tool. It discusses LCA methodologies and applications within the building sector, reviewing some of the life-cycle studies applied to buildings or building materials and component combinations within the last fifteen years in Europe and the United States. It highlights the problems of a lack of an internationally comparable and agreed data inventory and assessment methodology which hinder the application of LCA within the building industry. It identifies key areas for future research as (i) the whole process of construction, (ii) the relative weighting of different environmental impacts and (iii) applications in developing countries

Carbon Free Boston: Buildings Technical Report

Part of a series of reports that includes: Carbon Free Boston: Summary Report; Carbon Free Boston: Social Equity Report; Carbon Free Boston: Technical Summary; Carbon Free Boston: Transportation Technical Report; Carbon Free Boston: Waste Technical Report; Carbon Free Boston: Energy Technical Report; Carbon Free Boston: Offsets Technical Report; Available at http://sites.bu.edu/cfb/OVERVIEW: Boston is known for its historic iconic buildings, from the Paul Revere House in the North End, to City Hall in Government Center, to the Old South Meeting House in Downtown Crossing, to the African Meeting House on Beacon Hill, to 200 Clarendon (the Hancock Tower) in Back Bay, to Abbotsford in Roxbury. In total, there are over 86,000 buildings that comprise more than 647 million square feet of area. Most of these buildings will still be in use in 2050. Floorspace (square footage) is almost evenly split between residential and non-residential uses, but residential buildings account for nearly 80,000 (93 percent) of the 86,000 buildings. Boston’s buildings are used for a diverse range of activities that include homes, offices, hospitals, factories, laboratories, schools, public service, retail, hotels, restaurants, and convention space. Building type strongly influences energy use; for example, restaurants, hospitals, and laboratories have high energy demands compared to other commercial uses. Boston’s building stock is characterized by thousands of turn-of-the-20th century homes and a postWorld War II building boom that expanded both residential buildings and commercial space. Boston is in the midst of another boom in building construction that is transforming neighborhoods across the city. [TRUNCATED]Published versio

Identifying Barriers to Address During the Delivery of Sustainable Building Renovation Projects

Architects, engineers, and contractors are continuously searching for tools and methods to reduce the unique risks associated with the delivery of construction projects. Since national policies to reduce carbon emissions and energy consumption will require drastic improvements to the existing building stock, one specific area in need of such tools is the sustainable renovation of existing buildings. The purpose of this research is to identify the barriers to address during the delivery of sustainable renovation projects and offer solutions that overcome these barriers. For example, typical renovation projects do not coordinate energy retrofits with building system renovations, resulting in poor use of resources and inefficient building performance. Reaping multiple benefits from single expenditures and optimizing planned capital costs is a strategy for overcoming this barrier. This research searches for the best opportunities to improve the delivery of sustainable building renovation projects. A literature review and case study were performed to identify barriers to address during the delivery of sustainable renovation projects. Exploratory case study data was obtained through interviews with the project owner and contractor, site visits, and review of project documents. Results show that barriers found in sustainable renovation projects include issues regarding unforeseen existing conditions, interactions between building systems, financial analysis, and lack of experience, education, and awareness. Identifying methods to overcome these barriers may render existing buildings more sustainable. Methods for further exploration include: Policies and tools for promoting sustainable renovation, education and training of industry professionals and end-users, and enhancing the role of government and other public bodies to create a market demand for sustainable renovation