T. Williamson

Urban Microclimate : Designing the Spaces Between Buildings

Preface Introduction 1. Scales of Climatic Study 2. The Urban Energy Balance 3. The Urban Heat Island 4. Urban Airflow 5. The Energy Balance of a Human Being in an Urban Space 6. Thermal Preferences 7. Application of Climatology in Urban Planning and Design 8. Microclimate Design Strategies in Urban Space 9. Vegetation 10. Linear Space 11. Modelling the Urban Microclimate Case Study 1: Neve Zin Case Study 2: Clarke Quay Glossary

Multi-criteria assessment of building performance: theory and implementation

Abstract This paper presents the development of a building performance assessment methodology and tool that is intended to assist the design process. The methodology is based on a multi-criteria decision-making approach where the performance of the building is always compared to a reference building. This approach allows the designer to test design strategies against different sets of criteria. The methodology is implemented into an assessment tool whose features include a module for automatically generating the reference building, changeable databases, validated calculation engine, and a user-accessible assessment-criteria module. A case study is presented to explain the operation and implications of this tool.

An improvement of the CTTC model for predicting urban air temperatures

Abstract This paper presents an improvement of the CTTC model originally developed by Swaid and Hoffman, which makes it applicable in any fine weather situation. The model accounts for the effect of urban geometry and density on intra-urban variation of air temperatures. The application of the original model as an evaluative tool for practical urban design situations was limited by its restriction in use to fair weather (light wind and clear sky) conditions. In the improved CTTC method most of these restrictions are lifted. The accuracy of the new version is verified against measured data recorded in two canyons located at the University of Adelaide. The predicted temperature proved to be in good agreement with the measured temperature in different synoptic situations (cloudiness and wind speed and direction). An investigation is conducted to test the significance of incorporating the urbanisation effect to modify meteorological air temperature used in thermal simulation programs. The results indicate that it has a crucial effect on predicted energy use for space heating/cooling.

Urban Surface Energy Balance Models: Model Characteristics and Methodology for a Comparison Study

Many urban surface energy balance models now exist. These vary in complexity from simple schemes that represent the city as a concrete slab, to those which incorporate detailed representations of momentum and energy fluxes distributed within the atmospheric boundary layer. While many of these schemes have been evaluated against observations, with some models even compared with the same data sets, such evaluations have not been undertaken in a controlled manner to enable direct comparison. For other types of climate model, for instance the Project for Intercomparison of Land-Surface Parameterization Schemes (PILPS) experiments (Henderson-Sellers et al., 1993), such controlled comparisons have been shown to provide important insights into both the mechanics of the models and the physics of the real world. This paper describes the progress that has been made to date on a systematic and controlled comparison of urban surface schemes. The models to be considered, and their key attributes, are described, along with the methodology to be used for the evaluation.

Learning from thermal mavericks in Australia: comfort studies in Melbourne and Darwin

The research presented in this paper was conducted in order to test whether the thermal preferences of occupants in low-energy houses are influenced by their environmental values. This was done through a 12-month thermal comfort study and Environmental Attitudes Inventory (EAI) of 40 households in dwellings of non-standard construction located within two very different Australian climates: cool temperate – Melbourne and hot humid – Darwin. The results show that the occupants of these dwellings considered conditions comfortable often outside of the accepted adaptive thermal comfort limits and suggest that the conditions people find acceptable may be influenced by their underlying environmental values. These results indicate that greater acknowledgement of atypical preferences in the mandatory assessment of building thermal performance is needed.

The effect of internal environmental quality on occupant satisfaction in commercial office buildings

This article addresses a post-occupancy evaluation of a sample of office buildings in Adelaide, South Australia, which compares Green Star-rated against non-Green Star-rated buildings. Internal environment monitoring and occupant surveys were conducted to assess the perceived thermal, visual, and aural comforts, as well as health and productivity. The results show that Green Star-rated buildings provide slightly higher satisfaction in some thermal comfort aspects, but lower satisfaction in a number of significant elements, such as lighting and noise. Current trends in office design are, in some cases, seen to accentuate these issues. The results indicate that improvement in the design of buildings is an ongoing process that needs to be supported with effective and comprehensive feedback systems, including evaluation of the product in use, a system that is currently lacking in the commercial built environment.

The Implications for Building Ventilation of the Spatial and Temporal Variability of Air Temperature in the Urban Canopy Layer

Abstract Effective planning of building ventilation, whether passive or mechanically assisted, requires detailed information about external air temperature. This paper presents experimental evidence from Adelaide, Australia, that demonstrates substantial intra-urban variations in air temperature, whose magnitude changes across the urban space and as a function of time. A canyon air temperature computer model (CAT) capable of predicting air temperature in an urban street canyon for extended periods in a variety of weather conditions, on the basis of meteorological time series recorded at an open site exposed to the same meso-scale conditions, is then applied to illustrate the changes in the Climatic Cooling Potential (CCP) of selected urban locations when the effect of site-specific microclimate is taken into account.

A COMPARISON OF DOMESTIC EVAPORATIVE AND REFRIGERATIVE COOLING IN SOUTH AUSTRALIA

This recent study of domestic evaporative cooling and refrigerative cooling in South Australia and surrounding areas involved monitoring of one evaporatively cooled and one refrigeratively cooled house, followed by computer simulation of performance of a range of houses, cooling systems, and modes of operation in a representative range of South Australian climates. The study showed that evaporative coolers use about half as much energy as refrigerative coolers in well insulated houses in Adelaide and Mildura, ranging to about a quarter the energy in poorly insulated Alice Springs houses. Life-time costs are reduced to 50–65%. The use of evaporative cooling is shown to have important implications for choice of economic insulation levels and materials: improvements to the building fabric have little effect on the energy consumed by evaporative coolers, and such improvements are generally not justified by savings in evaporative cooling costs.

Designing houses for the Australian climate: the early research

The design of houses to suit the Australian environment has been a preoccupation from the first day that Europeans set foot on the shores of Port Jackson. Following WWII, a scientific approach to researching the relationship between building design and the climate commenced. From then and up to the present three periods of research can be identified. This paper concentrates on the first formative period between 1945 and 1972 when the thermal performance research work in Australia was dominated by two organizations, the Department of Works, Commonwealth Experimental Building Station (CEBS) located in Ryde, Sydney, and CSIRO, Division of Building Research (DBR) situated in Highett, Melbourne. During this period, thermal performance research conducted by these organizations was recognized throughout the world for its innovation. The paper summarizes the major work undertaken and how many of the concepts that informed this work are still with us today.

Earthship monitoring and thermal simulation

This paper describes the research which investigates the thermal performance of Earthship, an autonomous, earth-sheltered housing concept that claims to require no active heating or cooling systems despite extreme climatic conditions. This research aims to test these claims through monitoring and thermal simulations. The study involves monitoring the indoor conditions in an Earthship home in New Mexico, USA and uses the measured data to calibrate a computer model used to simulate the thermal performance of the home for further analyses. The second part of the study compares Earthship thermal performance located in a temperate climate in Australia with that of buildings incorporating different wall construction materials such as strawbale, rammed earth, and brick veneer. Results from both these studies substantiate the claims. The effect of including a greenhouse, earth berm, and internal wall material is also explored and quantified. The paper concludes with a discussion of the scope for reducing home energy use through the use of Earthship design principles and construction methods and the viability for building these houses in the Australian suburbs.