The Performance of Natural Ventilation In A Dance Studio – Lessons From Tracer Gas Measurements And Control Integration

The naturally ventilated, three storey School of Arts Jarman Building provides two dance studios, an exhibition gallery, teaching rooms, video editing suites and offices. The main dance studio is double-height, has underfloor heating and accommodates sixty people. Fresh air enters from low level perimeter louvres and exits at high level through a stack that rises through the third storey to a stack terminal with motorized louvres. Tracer gas (CO2) measurements were used to measure the ventilation rate in conjunction with hot-wire anemometry in the stack tower. The results showed that when all air inlet and exit louvres were set to closed, the residual air flow up the stack was 0.33m3/s representing a potential heat loss of 9kW in winter at 0°C outside. When the louvres were all open, the air flow increased to between 0.49 and 0.62m3/s, a level consistent with the studio’s design occupancy. It was found that the studio’s 4m high perimeter curtains represent a barrier to fresh air entering the main room space and cause the incoming air to migrate upwards towards the stack exit and effectively bypass the central part of the studio. Tracer gas decay rates showed that the main space experienced an air exchange rate 50% less than that for the overall studio. An investigation of the controls also revealed that the underfloor heating system operated independently of the control of the stack ventilation system, leading to simultaneous heating and venting. The research shows the vital importance of prescribing contractually that key controls are integrated, that fresh air dampers are well-sealed when closed, and the importance of designing a fresh air supply that matches the way a space is used

The influence of hospital ward design on resilience to heat waves: An exploration using distributed lag models

Distributed lag models (DLMs) to predict future internal temperatures have been developed using the hourly weather data and the internal temperatures recorded in eleven spaces on two UK National Health Service (NHS) hospital sites. The ward spaces were in five buildings of very different type and age. In all the DLMs, the best prediction of internal temperature was obtained using three exogenous drivers, previous internal temperature, external temperature and solar radiation. DLMs were sensitive to the buildings’ differences in orientation, thermal mass and shading and were validated by comparing the predictions with the internal temperatures recorded in the summer of 2012. The results were encouraging, with both modelled and recorded data showing good correlation. To understand the resilience of the spaces to heat waves, the DLMs were fed with weather data recorded during the hot summer of 2006. The Nightingale wards and traditional masonry wards showed remarkable resilience to the hot weather. In contrast, light-weight modular buildings were predicted to overheat dangerously. By recording internal temperatures for a short period, DLMs might be created that can forecast future temperatures in many other types of naturally ventilated or mixed-mode buildings as a means of assessing overheating ris

The impact of urban compactness, comfort strategies and energy consumption on tropical urban heat island intensity: a review

The importance of studying tropical urban climate was recognised by the World Meteorological Organisation (WMO) as early as in 1981 but substantial improvements were seen only in the last two decades. However specific knowledge of tropical urban climate still lags behind that of temperate climate. In this paper, authors review the state of the art in tropical heat island intensity, its influence on building energy consumption and the effect of urban compactness in the tropics. The review is limited to peer-reviewed journal publications found on four databases: Web of Science, Scopus, Google Scholar and Science Direct. The review indicates that although the tropical belt has large variations in topography, forest cover, land mass and development patterns, much of the current work is confined largely to Far East Asia, South Asia and South America. Future studies should focus on protocol for parameterisation and standardisation of measurement, in depth and scientific understanding of the influence of vegetation, water and topography, survey and monitoring of the context specific relationship between UHI and energy consumption, development of database for numerical model validation and improvement, and the context specific development of LCZ based institutional framework to integrate UHI mitigation strategies with environmental design guidelines

Combustion chamber analysis code

A three-dimensional, time dependent, Favre averaged, finite volume Navier-Stokes code has been developed to model compressible and incompressible flows (with and without chemical reactions) in liquid rocket engines. The code has a non-staggered formulation with generalized body-fitted-coordinates (BFC) capability. Higher order differencing methodologies such as MUSCL and Osher-Chakravarthy schemes are available. Turbulent flows can be modeled using any of the five turbulent models present in the code. A two-phase, two-liquid, Lagrangian spray model has been incorporated into the code. Chemical equilibrium and finite rate reaction models are available to model chemically reacting flows. The discrete ordinate method is used to model effects of thermal radiation. The code has been validated extensively against benchmark experimental data and has been applied to model flows in several propulsion system components of the SSME and the STME

Hospital wards and modular construction: Summertime overheating and energy efficiency

The UK National Health Service (NHS) is continually under pressure to provide more bed spaces and to do this within a tight budget. Therefore, NHS Trusts may turn to modular buildings, which promise faster construction and low energy demands helping the NHS meet its stringent energy targets. However, there is growing evidence that thermally lightweight, well insulated and naturally ventilated dwellings are at risk of overheating during warm UK summers. This paper examines the energy demands and internal temperatures in two 16-bed hospital wards built in 2008?at Bradford Royal Infirmary in northern England using modular fast track methods. The two-storey building used ceiling-mounted radiant panels and a mix of natural and mechanical ventilation with heat recovery to condition patients' rooms. Monitoring showed that the annual energy demand was 289?kWh/m2 ±16%, which is below the NHS guidelines for new hospital buildings. It was observed that the criterion given in Department of Health Technical Memorandum HTM03-01 can lead to the incorrect diagnosis of overheating risk in existing buildings. Assessment using other static and adaptive overheating criteria showed that patient rooms and the nurses' station overheated in summer. To maintain patient safety, temporary air conditioning units had to be installed during the warmest weather. It is concluded that thermally lightweight, well insulated, naturally ventilated hospital wards can be low-energy but are at risk of overheating even in relatively cool UK summer conditions and that this needs to be addressed before such buildings can be recommended for wider adoption

Experimental investigation of the impact of urban fabric on canyon albedo using a 1:10 scaled physical model

This paper presents findings from a large-scale experiment on the impact of urban fabric on canyon albedo, aimed at informing the development of an urban albedo calculator for London, an empirical model to predict changes in urban albedo in relation to changes in urban fabric and solar altitude. Through different material applications on a 1:10 scaled physical model of an actual residential area, the study assessed the effect of street-level materials and three common façade types on canyon albedo alongside the canyon’s reflective power in the infrared, and the impact of rain. The results showed that the addition of concrete paving at street level increased canyon albedo by 9%, while the substitution of tarmac with grass by 70%. Brickwork and aluminium cladding façades were seen to contribute to significantly higher canyon albedo than curtain wall across the measured irradiance spectrum. The results also revealed the highly dynamic nature of canyon albedo and a consistent rainfall-induced reduction of albedo in the range 22-36% throughout the experimental phases. The findings from this study can inform urban planning and policy making directed at tackling the urban heat island effect

Impact of urban albedo on microclimate: Computational investigation in London

The urban albedo (UA), defined as the ratio of the reflected to the incoming shortwave radiation at the upper edge of urban canyons, quantifies their ability to reflect solar radiation towards the sky. This research investigates the impact of real-world urban geometries and optical properties of facades and roads materials on the UA and street level microclimate in London. The Indexed Sphere (IVS) algorithm of ENVI-met 4.4.4 is used to compute the UA of several canyon configurations. The accuracy of the IVS algorithm is evaluated against measurements on a 1:10 physical model reproducing the geometry and materials of the case study area. The simulation results show that reflective materials applied to the canyon surfaces are more effective in increasing the UA of canyons with low aspect ratios. The use of reflective materials in urban canyons always increases the amount of reflections at the street level, increasing the mean radiant temperature in most cases. Air temperature is not affected by the canyon’s façades reflectivity while it shows a significant daytime reduction for increased roads’ reflectivity. The results provide preliminary guidelines for the control of UA and the improvement of microclimate in London.EPSRC UK under the project ‘Urban albedo computation in high latitude locations: An experimental approach’ (EP/P02517X/1).https://www.conftool.org/plea2020/index.php/SC-5-4-Impact_Of_Urban_Albedo_On_Microclimate_Salvati_1751_b.pdf?page=downloadPaper&filename=SC-5-4-Impact_Of_Urban_Albedo_On_Microclimate_Salvati_1751_b.pdf&form_id=1751&form_index=2&form_version=fina