energy

This paper presents the development and implementation of an Energy-based Decision Support System (EDSS) that will enhance the selection process of replacement building features. EDSS includes dynamic databases that utilize data/web mining concepts, Knowledge Base System (KBS) and a thermal simulation engine. The system allows decisions to be made based on a long-term vision incorporating energy cost savings rather than immediate needs. A stand-alone application was implemented based on EDSS.

This paper presents a set of solutions to enable  differential time scales for dynamic boundary conditions within whole-building energy simulation, specifically occupant behavioral adaptations in response to short-term changes in solar and daylighting conditions. The concept is to allow specialized libraries to determine in tandem the state of critical variables, such as window blinds and lighting systems, at higher frequencies than the building domain time step (e.g.

As strategies for improving building envelope and HVAC equipment efficiencies are increasingly required to reduce building energy use, a greater percentage of energy loss will occur through building envelope leakage. Although the energy impacts of unintended infiltration on a building's energy use can be significant, current energy simulation software and design methods are generally not able to accurately account for envelope infiltration and the impacts of improved airtightness.

Fuel cells are highly efficient energy conversion systems that have recently gained significant interest in terms of both science and applications. Exergy analysis is adopted here for a power plant involving SOFC with external steam reforming that is fuelled by modeled biogas/steam mixtures. The electrical efficiency has been estimated and the effect of various operational parameters on the process efficiency has been investigated.

The importance of adventitious air leakage under normal operational conditions and its reduction in order to save energy is highlighted by the relvant building standards of many countries. This operational leakage is often inferred via the measurement of air permeability, a physical property of a building that indicates the resistance of its fabric to airflow. A building’s permeability is the measure of airflow rate through its envelope at a constant pressure differential of 50 Pascals.

Hybrid ventilation (HV), as a combination of automated natural ventilation (NV) and balanced mechanical ventilation (MV), provides opportunities to use the advantages of both ventilation systems during the seasons in order to reduce energy demand and at the same time obtain comfortable indoor climate.

The airtightness of office and educational buildings influences energy use and thermal comfort. A leaky building is likely to have a high use of energy and thermal discomfort. The knowledge of real airtightness levels of entire buildings and their impact on the energy use is very low, except for a study carried out in the USA. Therefore two different methods of airtightness testing were applied to six entire Swedish office and educational buildings built since 2000. The first method involves using the ventilation system of the building and the second one to use a number of blower doors.

Today an acceptable indoor air quality is mainly defined by specifying the required level of ventilation in air changes per hour or the outside air supply rate. This would be equivalent to defining the requirements for thermal comfort by specifying the level of heating or cooling in Watts. The increasing societal need for energy efficiency will often result in very tight buildings. This means that the amount of outside air supplied by infiltration is not enough to provide the required ventilation.

A retrofit study was conducted in an unoccupied manufactured house to investigate the impacts of airtightening on ventilation rates and energy consumption. This report describes the retrofits and the results of the pre- and post-retrofit assessment of building airtightness, ventilation, and energy use. Building envelope and air distribution systems airtightness were measured using fan pressurization. Air change rates were measured continuously using the tracer gas decay technique.

In this study, the concept of the Hybrid air-conditioning system utilizing convection and radiation heat exchange will be suggested. In this paper, the heat removal characteristics of Hybrid air-conditioning system will be described by theoretical review and experimental methods. Also the ratio of cooling load removed by Hybrid air-conditioning system could be divided as radiation and convection heat exchanges. The methods could be used to system design of Hybrid air-conditioning system.