Building Energy Performance Simulation Research Articles

Modelling and Performance Evaluation of Solid Oxide Fuel Cell for Building Integrated Co‐ and Polygeneration

AbstractModels of fuel cell based combined heat and power systems, used in building energy performance simulation codes, are often based on simple black or grey box models. To model a specific device, input data from experiments are often required for calibration. This paper presents an approach for the theoretical derivation of such data. A generic solid oxide fuel cell (SOFC) system model is described that is specifically developed for the evaluation of building integrated co‐ or polygeneration. First, a detailed computational cell model is developed for a planar SOFC and validated with available numerical and experimental data for intermediate and high temperature SOFCs with internal reforming (IT‐DIR and HT‐DIR). Results of sensitivity analyses on fuel utilisation and air excess ratio are given. Second, the cell model is extended to the stack model, considering stack pressure losses and the radiative heat transfer effect from the stack to the air flow. Third, two system designs based on the IT‐DIR and HT‐DIR SOFCs are modelled. Electric and CHP efficiencies are given for the two systems, as well as performance characteristics, to be used in simulations of building integrated co‐ and polygeneration systems.

Microclimatic control in the museum environment: Air diffusion performance

For the conservation of cultural heritage, museums need appropriate HVAC systems. Besides the time stability of the microclimatic parameters in the exhibition rooms, a high spatial uniformity is necessary and, thus, an optimal performance of the air diffusion systems. Using numerical codes based on Building Energy Performance Simulation (BEPS) and Computational Fluid Dynamics (CFD) techniques, in this paper an analysis has been carried out to compare different suitable air diffusion equipments, as regards uniformity of thermal-hygrometric and kinetic fields in a modelled typical exhibition room. For various part load conditions, the values of thermal-hygrometric parameters in different volumes of the room have been evaluated, as well as an innovative spatial thermal-hygrometric performance index. Globally estimating indoor temperature, relative humidity and their uniformity, for high exhibition rooms (5 m) the swirling diffusers have shown the best average performances, followed by the perimetrical stripes of slot diffusers, while for very high rooms (9 m) nozzles have resulted preferable.

A database of house descriptions representative of the Canadian housing stock for coupling to building energy performance simulation

The development of a simulation tool that can accurately characterize the energy performance of the Canadian housing stock would enable detailed studies to predict the impact of energy saving upgrades and technologies on a national scale. Such a tool requires a detailed database of house descriptions that collectively represent the entire housing stock. Such a database has been assembled by selectively extracting measured and observed data collected by professionals who conducted on-site audits of 200,000 houses. The auditors' data were extracted to statistically match key parameters (location, house type, vintage, geometry and heating system) with a broad-based random survey of the Canadian stock. The result is a database comprised of nearly 17,000 detailed records of single-detached, double and row houses. Each of these house records represents ∼500 houses in the Canadian stock and contains sufficient data to enable the accurate characterization of its energy performance through building performance simulation.

Contrasting the capabilities of building energy performance simulation programs

For the past 50 years, a wide variety of building energy simulation programs have been developed, enhanced and are in use throughout the building energy community. This paper is an overview of a report, which provides up-to-date comparison of the features and capabilities of twenty major building energy simulation programs. The comparison is based on information provided by the program developers in the following categories: general modeling features; zone loads; building envelope and daylighting and solar; infiltration, ventilation and multizone airflow; renewable energy systems; electrical systems and equipment; HVAC systems; HVAC equipment; environmental emissions; economic evaluation; climate data availability, results reporting; validation; and user interface, links to other programs, and availability.

04/02599 Building energy performance simulation as partof interoperable software environments: Bazjanac, V. Building and Environment, 2004, 39, (8), 879–883

04/02599 Building energy performance simulation as partof interoperable software environments: Bazjanac, V. Building and Environment, 2004, 39, (8), 879–883

Building energy performance simulation as part of interoperable software environments

Interoperable software makes it possible to seamlessly exchange data among different compliant applications. Among other benefits, this offers opportunities to increase the quality of building energy simulation through simultaneous interaction of multiple design and simulation tools, possible because of direct data exchange among them. This paper discusses the new IFC HVAC extension schemata that are included in the latest release of the IFC data model (IFC2×2) and the new functionalities and industry processes it now supports. It describes an example of interoperable software environment, possible gains from interoperable simulation, and discusses current issues in data exchange for such simulation.

Simplified algorithms for the Italian energy rating scheme for fenestration in residential buildings

Energy consumption in buildings is responsible for 40% of the energy end use in Italy. Most of the thermal and solar exchanges between the building and the external environment depend on fenestration. Rating schemes are useful instruments for classifying the energy efficiency of devices in many fields. For windows a rating system is largely utilised in some countries and is under study or development in many others. In Italy, single glazed units represent 80% of the total installed windows and the percentage of high quality products can be considered negligible. An energy-rating system would encourage efficient products onto the Italian market and would accelerate technical innovations in the glass and frame industries. The aim of introducing this scheme is to greatly reduce energy end use and, as a consequence, also CO 2 emissions. The methodology, implemented for the residential sector, is based on the assessment of thermal performances of three reference buildings as a function of: window properties, climatic data and architectural characteristics. More than 1000 simulations, run with a building energy performance simulation code (TRNSYS), has made it possible to evaluate specific and percental heating, cooling and total energy savings as well as the reduction in CO 2 emissions for the selected buildings. The simplified algorithms, which the energy-rating scheme for both cold and hot seasons is based on, have been taken from the analysis of previous results. Examples of cost–benefits analysis are presented to stress the economical and environmental advantages of the proper application of this instrument.

A design day for building load and energy estimation

We describe how a design day for building energy performance simulation can be selected from a typical meteorological year of a location. The advantages of the design day weather file are its simplicity and flexibility in use with simulation programs. The design day is selected using a weather parameter comprising the daily average dry bulb temperature and total solar insolation. The selection criterion addresses the balance between the need to minimise the part-load performance of the air-conditioning systems and plants and the number of hours of load not met. To validate the versatility of the design day weather file, we compare simulation results of the peak load and load profile of a building obtained from the DOE-2.1E code and a specially developed load estimation program, PEAKLOAD. PEAKLOAD is developed using the transfer function method and ASHRAE databases. Comparative results are in good agreement, indicating that a design day thus selected can be used when quick answers are required and simulations using a TMY file cannot be easily done or justified.

Effects of standard energy conserving measures on thermal comfort

Building energy performance simulation programs such as DOE-2 neglect thermal comfort. They basically assume that control of air temperature is synonymous with thermal comfort control. The present study accounts for other factors in thermal comfort such as air velocity and mean radiant temperature. A 31-story office building has been studied in both Chicago and Miami. DOE-2 was used to predict the building energy performance for three energy conservation measures. The output from DOE-2 was then used to determine the consequences on thermal comfort.