Office Of Building Technology Research Articles

Evolutionary algorithm-based design of acoustic metamaterials for thermal insulation

Heat transfer at the nanoscale is an acoustic problem. In nonmetallic solids, heat is primarily carried by lattice vibrations (phonons), and its transfer can similarly be impeded by methods for manipulating vibrations familiar to acousticians. Metamaterials have seen increasing use in altering and controlling vibration. Metamaterial concepts, including periodic structuring of materials and introduction of resonant inclusions, have been used to control vibration on the macroscale, and can also affect heat transfer when implemented at nanoscale. Locally resonant materials appear to be able to address the frequency range responsible for heat transfer most easily. Control of heat transfer is of particular importance because heating and cooling buildings are among the most extensive human uses of energy, thus presenting a significant opportunity for societal benefit through increased efficiency. Even modest improvements in building insulation will result in significant energy and cost savings. In pursuit of a superior and cost-effective insulating material for building applications, an optimization of the nanostructure of a polymer metamaterial panel to reduce heat transfer is carried out using simulation in COMSOL and a genetic algorithm. Results of this research are presented here. [Funded by USDOE Office of Energy Efficiency and Renewable Energy (EERE)—Office of Building Technologies.]

Energy Performance and Economic Feasibility Study of Historical Building in the City of Matera, Southern Italy

In this paper a careful energy audit and an energy restoration of some historical buildings was performed. In particular, three cultural heritages buildings situated in the city of Matera in Southern Italy were analysed. To analyse these buildings, an integrated approach based on measurements in situ and on dynamic energy simulations was used. Then, some energy efficiency actions were performed, safeguarding the authenticity value of these structures. The thermal conductance, the indoor temperature and the energy consumption were measured in situ and then the numerical virtual model was created by the Energy Plus code (Energy Plus is free, open-source, and cross-platform developed by the U.S. Department of Energy’s and Building Technologies Office) (U.S. Department of Energy’s (DOE) Building Technologies Office (BTO), Washington, DC, USA). The numerical model was validated by using the Inequality Coefficient (IC) and then different parametric energy analyses were performed. The paper analysed different energy improvements and a techno-economic feasibility study was performed for each improvement. This analysis was conducted in dynamic regime by using the Energy-Plus code. In these buildings the thermal system improvements have a better payback time than envelope improvements. Two different thermal system improvements were analysed: the absorption heat pump with thermostatic valves and the compression heat pump with fan coil unit. Moreover, the replacement of present lighting with LED technologies has a payback time near one year.

Transactional network: Improving efficiency and enabling grid services for buildings

Because of a need to reduce electricity consumption and to make electricity generation cleaner, there is an impetus to improve the energy efficiency of the building stock and widespread installation of distributed variable renewable energy generation. Soon, a significant fraction of transportation energy will be in the form of electricity. Significant gains in building operational efficiency are possible because between 20% and 30% of the energy consumed in commercial buildings is typically wasted because of poor or inefficient building operations. To address these problems, the U.S. Department of Energy's Building Technologies Office is supporting the development of the concept of a “transactional network” that supports energy, operational, and financial transactions between building systems (e.g., rooftop units), and the electric power grid using applications, or “agents,” that reside either on the equipment, on local building controllers, or in the Cloud. This article describes the transactional network concept, the platform, and two example agents/applications within VOLTTRON™ that improve operational efficiency and enable grid services for packaged air conditioners and heat pumps (rooftop units). It also describes the results from testing the concept at some demonstration sites.

(Invited) Beyond Vapor Compression Technologies

The Building Technologies Office (BTO) of the U.S. Department of Energy (DOE) seeks to accelerate the development of the next generation of heating, ventilation, and air-conditioning (HVAC) technologies, including both electric- and natural-gas-driven solutions. HVAC is the largest energy end-use for U.S. buildings, consuming approximately 37.3% (~15 Quads) of total energy.[1] Vapor compression based systems have effectively and efficiently served the HVAC needs for residential and commercial buildings for close to 100 years. Vapor compression technologies are currently the dominant HVAC technology due to their scalability, relatively compact size, high reliability, and other attributes. However, the refrigerants used in these systems have detrimental global effects on the environment when released into the atmosphere. The scientific community has responded to such environmental threats by several proposals to phase down refrigerants with large global warming potential (GWP). What is needed is a paradigm shift in HVAC technologies, moving beyond today’s refrigerants and toward a future based (at least in part) on non-vapor-compression HVAC technologies with the ultimate goal to eliminate high GWP refrigerants all together. This new paradigm is the ultimate environmental solution (zero GWP cooling fluids), provides energy savings for consumers, and will enable manufactures to avoid the challenge of future refrigerant change out cycles. A primary objective is to focus on an end-state with no refrigerants required, while enabling U.S. manufacturers to innovate in ways that will enhance their competitiveness over the longer term. What comes after vapor compression technology? U.S. Department of Energy has recently completed a report on the Energy Savings Potential and RD&D Opportunities for Non-Vapor-Compression HVAC Technologies to help frame the state of these next generation technologies. Possible candidate technologies include, but are not limited to: sorption technologies, alternative thermodynamic cycles, solid state technologies, membrane technologies, electrochemical cycles , and mechanical technologies. BTO currently has several projects that use electrochemical cycles in its HVAC, Water Heating and Appliance R&D portfolio. [1] http://buildingsdatabook.eren.doe.gov/

The Blue LED Nobel Prize: Historical context, current scientific understanding, human benefit

The Blue LED Nobel Prize: Historical context, current scientific understanding, human benefit

Improved structural and electrical properties of thin ZnO:Al films by dc filtered cathodic arc deposition

Abstract

06/01949 Life-cycle cost analysis of energy efficiency design options for residential furnaces and boilers: Lutz, J. et al. Energy, 2006, 31, (2–3), 311–329

LBNL-53950 Life-Cycle Cost Analysis of Energy Efficiency Design Options for Residential Furnaces and Boilers James Lutz, Alex Lekov, Camilla Dunham Whitehead, Peter Chan, Steve Meyers, and James McMahon Energy Analysis Department Environmental Energy Technologies Division Ernest Orlando Lawrence Berkeley National Laboratory University of California Berkeley, CA 94720 January 2004 This work was supported by the Office of Building Technologies and Community Systems of the U.S. Department of Energy, under Contract No. DE-AC03-76SF00098.

Preliminary Results from an Advanced Lighting Controls Testbed

LBNL-41633 L-212 Presented at the IESNA 1998 Annual Conference, San Antonio, TX, August 10-12, 1998, and to be published in the Proceedings and considered for p`ublication in the JIES. Preliminary Results from An Advanced Lighting Controls Testbed Francis Rubinstein, Judith Jennings, Douglas Avery Building Technologies Program Environmental Energy Technologies Division Ernest Orlando Lawrence Berkeley National Laboratory University of California Berkeley, California, USA 94720 Steven Blanc Pacific Gas & Electric Co. Customer Energy Management Dept., Research & Development Group 2303 Camino Ramon, Suite 100 San Ramon, California, USA 94583 March 1998 This work was supported by the General Services Administration, Pacific Rim Region; the Pacific, Gas & Electric Co.; and the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Federal Energy Management Programs and by the Office of Building Technology, State and Community Programs, Office of Building Equipment of the U.S. Department of Energy under Contract No. DE-AC03-76SF00098.