Application of Passive Downdraught Evaporative Cooling (PDEC) to Non-Domestic Buildings

Researchers

Neil Bowman, Kevin. Lomas,
Malcolm Cook, Herbert Eppel

Source of Funding

EU Joule Programme

Duration

3 years

Collaborators

Ford and Associates, Mario Cucinella, Microlide, Conphoebus, University of Malaga

Aims

To establish the technical and financial feasibility of PDEC
To monitor the performance of PDEC systems
To illustrate the application of PDEC in new and refurbishment building designs
To illustrate the energy and environmental benefits of PDEC
To explore the applicability of detailed simulation models for predicting PDEC

Background

Passive Downdraught Evaporative Cooling (PDEC) is a low energy technique for cooling and ventilating buildings which works by spraying microscopic water particles into a warm dry airstream which evaporate, thereby raising the relative humidity of the air and reducing its temperature. This denser-than-ambient air then falls into a 'capture zone' from where it can be drawn into occupied spaces. The computer modelling teams at the IESD and the University of Malaga were responsible for developing techniques for modelling PDEC using computational fluid dynamics and dynamic thermal simulation programs. These techniques were validated using experiments undertaken in Sicily and then applied to new and refurbished building designs proposed by the architects.

Findings

PDEC, in combination with some mechanical cooling at certain times of year, is a technically and economically viable alternative to full air conditioning in hot dry climates
PDEC is not a 'clip-on' technology, rather, it needs a level of understanding on the part of the architect and engineer about the impact which the building's design has on the performance of PDEC systems.
Computational fluid dynamics and dynamic thermal simulation techniques were developed for assessing PDEC building designs. They were used successfully for helping to size ventilation openings, assessing wind effects and for determining energy savings.

Publications

Bowman N. T., Eppel H., Lomas K. J., Robinson D. and Cook M. J. Passive Downdraught Evaporative Cooling - I: Concept and Precedents, Indoor and Built Environment, in press, 2001.

Cook M. J., Robinson D., Lomas K. J. and Bowman N. T. Passive Downdraught Evaporative Cooling - II: Airflow Modelling, Indoor and Built Environment, in press, 2001.

Robinson D., Eppel H., Cook M. J., Lomas K. J. and Bowman N. T., Passive Downdraught Evaporative Cooling - III: Thermal Modelling, Indoor and Built Environment, in press, 2001.

Robinson D., Cook M. J., Lomas K. J. and Bowman N. T. Passive Downdraught Evaporative Cooling - IV: Design and Control, Indoor and Built Environment, in press, 2001.