Conference Agenda

This paper discusses the cooling potential of three types of green roofs, insulated, uninsulated, radiant-evaporative, evaluated with test cells. Different rules and schedules were tested for irrigation, water movement through the radiant pipes, plenum fan operation, and cooling with outside air. Results indicate that on warm days with maximum outdoor temperatures below 32 °C the uninsulated green roof will perform better and on drier days up to 44 °C and a Wet Bulb Temperature below 24 °C, the green roof with a radiant system and evaporative cooling performs better. On very warm days with high maximum temperatures above 33 °C the insulated green roof and the insulated roof (non-green) perform better. Optimum zones for the green roofs are plotted on the Building Bioclimatic Chart.

Buildings in Saudi Arabia consumes approximately 80% of the electricity generated in the country. Saudi Arabia’s hot, arid climate, with summer temperatures frequently exceeding 45°C, means that air conditioning uses nearly 50% of the country’s electricity, and virtually all the electricity is generated from fossil fuels. Passive cooling techniques could be a sustainable alternative to conventional air-conditioning systems when integrated properly within a building. A Passive Downdraught Evaporative Cooling (PDEC) tower is considered as one of the most efficient passive systems and was investigated in this study. A single storey open plan room with a PDEC tower was digitally modelled and then changes in wind direction and architectural form were simulated to see the effect on the PDEC performance. IES VE software was selected for the simulations as it can conduct a dynamic thermal simulation for PDEC systems. A weather file for Riyadh was obtained from the software Meteonorm. The study demonstrated that significant cooling can be achieved by PDEC towers, but that their effectiveness was greatly reduced by changes in wind direction linked to opening distributions in the room attached to the PDEC tower.

This research proposes a new set of equations that predict conditions at the outlet of a single stage passive downdraft evaporative cooling tower (PDECT) as well as a multi-stage passive and hybrid downdraft cooling tower (PHDCT), namely temperature drop (∆T) and air velocity (V). Equations were developed through multiple linear regression using data collected from experimental evaluation conducted during Summer, 2017 in Tempe, Arizona on built prototypes of these towers. Regression analysis indicated a strong correlation between measured and predicted data with an adjusted coefficient of determination ranging between 0.80 and 0.95.

Dry Mist technology targets basic human needs by improving micro climatic conditions to create a healthy and comfortable outdoor environment. The technology can be integrated into the design of public spaces, streetscapes, markets, playgrounds and parks to permit intense outdoor activities and to counter the effects of urban heat islands. This paper is about the results of a performance demonstration of Dry Mist Systems in the Cayman Islands. The systems have been successful tested under tropical conditions in open public spaces, plazas and restaurants.