• Energy Research

Abstract An increasingly popular solution for ventilation that facilitates strategies such as night cooling is the provision of purpose provided ventilation openings comprised of horizontal slotted architectural louvres. Often these are employed in single sided ventilation strategies where there exists an irregular unsteady interaction of wind and buoyancy forces. This paper presents results from full scale experimental measurements of the macroscopic Air Change Rate (ACR) for an opening utilising an architectural slotted louvre in zero2020/NBERT, a National Building Energy Retrofit Testbed in Cork, Ireland. 2 slot louvre cases and 3 plain opening cases were investigated with 44 tracer gas concentration decay tests completed in a single cell isolated office space. The findings show that, for similar boundary conditions, the spectral characteristics of the velocity in the opening are modified by the introduction of the slot louvre. A non-dimensional analysis highlights stronger wind dominant aeration for the louvre than a plain opening having comparable overall facade opening dimensions. On average across the various cases measured, the slot louvre ACR were 6.5% higher compared with the plain opening ACR with even greater increases when considering comparable free opening area cases specifically. A sensitivity analysis using stepwise multiple linear regression also demonstrated a high correlation between ACR, wind speed and wind direction for the slot louvre. A comparison of existing single sided correlations showed lower prediction error for the plain opening cases than for the slot louvre. When considering the dimensionless exchange rate parameter, F r , the published values for plain openings was comparable to those in this study but were too low in general for the slot louvre. An alternative value for this is suggested based on the field study measurements.

Abstract An increasingly popular solution for ventilation that facilitates strategies such as night cooling is the provision of purpose provided ventilation openings comprised of horizontal slotted architectural louvres. Often these are employed in single sided ventilation strategies where there exists an irregular unsteady interaction of wind and buoyancy forces. This paper presents results from full scale experimental measurements of the macroscopic Air Change Rate (ACR) for an opening utilising an architectural slotted louvre in zero2020/NBERT, a National Building Energy Retrofit Testbed in Cork, Ireland. 2 slot louvre cases and 3 plain opening cases were investigated with 44 tracer gas concentration decay tests completed in a single cell isolated office space. The findings show that, for similar boundary conditions, the spectral characteristics of the velocity in the opening are modified by the introduction of the slot louvre. A non-dimensional analysis highlights stronger wind dominant aeration for the louvre than a plain opening having comparable overall facade opening dimensions. On average across the various cases measured, the slot louvre ACR were 6.5% higher compared with the plain opening ACR with even greater increases when considering comparable free opening area cases specifically. A sensitivity analysis using stepwise multiple linear regression also demonstrated a high correlation between ACR, wind speed and wind direction for the slot louvre. A comparison of existing single sided correlations showed lower prediction error for the plain opening cases than for the slot louvre. When considering the dimensionless exchange rate parameter, F r , the published values for plain openings was comparable to those in this study but were too low in general for the slot louvre. An alternative value for this is suggested based on the field study measurements.

AbstractThis paper presents the results of a computational study on the energy consumption and related CO2 emissions for heating and cooling of an office building within the Urban Heat Island of London, currently and in the future. The study developed twenty weather files in an East-West axis through London; the weather files were constructed according to future climate change scenario for 2050 suitable for the UK which have been modified to represent specific locations within the London UHI based on measurements and predictions from a program developed for this purpose (LSSAT). The study simulated an office with typical construction, heat gains and operational patterns with an advanced thermal simulation program (IESVE). The predictions confirm that heating load decreases, cooling load and overheating hours increase as the office location moves from rural to urban sites and from present to future years. It is shown that internal heat gains are an important factor affecting energy performance and that night cooling using natural ventilation will have a beneficial effect at rural and city locations. As overheating will increase in the future, more buildings will use cooling; it is shown that this might lead to a five-fold increase of CO2 emission for city centre offices in London in 2050. The paper presents detailed results of the typical office placed on the East-West axis of the city, arguing the necessity to consider using weather files based on climate projections and urban heat island for the design of current buildings to safeguard their efficiency in the future.

AbstractThis paper presents the results of a computational study on the energy consumption and related CO2 emissions for heating and cooling of an office building within the Urban Heat Island of London, currently and in the future. The study developed twenty weather files in an East-West axis through London; the weather files were constructed according to future climate change scenario for 2050 suitable for the UK which have been modified to represent specific locations within the London UHI based on measurements and predictions from a program developed for this purpose (LSSAT). The study simulated an office with typical construction, heat gains and operational patterns with an advanced thermal simulation program (IESVE). The predictions confirm that heating load decreases, cooling load and overheating hours increase as the office location moves from rural to urban sites and from present to future years. It is shown that internal heat gains are an important factor affecting energy performance and that night cooling using natural ventilation will have a beneficial effect at rural and city locations. As overheating will increase in the future, more buildings will use cooling; it is shown that this might lead to a five-fold increase of CO2 emission for city centre offices in London in 2050. The paper presents detailed results of the typical office placed on the East-West axis of the city, arguing the necessity to consider using weather files based on climate projections and urban heat island for the design of current buildings to safeguard their efficiency in the future.

This is the post-print version of the final paper published in Journal of Energy and Buildings. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V.

This is the post-print version of the final paper published in Journal of Energy and Buildings. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2011 Elsevier B.V.

Abstract This paper evaluates one option to replace traditional cooking fuels in developing economies with a flexible, modular and clean solution of solar hydrogen, based on a numerical and experimentally tested system to address technical and safety issues. The study focuses on Ghana, Jamaica and Indonesia as examples of developing economies using fossil fuels for domestic cooking. Statistical analyses are performed and the domestic cooking demand profiles are created for these countries based on available data and a specific quantitative study in Ghana. The derived cooking demand profiles are used to size solar hydrogen plant case-studies for rural communities based on a TRNSYS numerical model. The results indicate that hydrogen plant sizing and management satisfy annual cooking demands of the communities which are 621.6 kg H2 for Jamaica, 631 kg H2 for Indonesia and 785 kg H2 for Ghana. The effect of the weather data on the simulation is estimated by comparison between TMY and recent weather data for Jamaica. Finkelstein-Schafer statistics indicate differences between the composite and recent weather data, but these prove to have minor effect on simulation results, with 0.9% difference in hydrogen generation. The potential to establish solar hydrogen plants in the countries is further evaluated by creating novel solar hydrogen potential maps.