Energy Efficiency in Buildings
Head of Sub-Group:Dr YG Yohanis
Members of Sub-Group:Professor NJ Hewitt, Professor H Elkadi, Dr T Hyde, Dr P Griffiths, Dr Y Fang, Dr J Mondol
Activities:Advanced Glazing, Thermal Energy Storage, Advanced Heat Pumps, Day Lighting
Advanced Glazing (Dr T Hyde):Energy Efficiency in Buildings has major programmes based on the development of advanced vacuum glazing, the use of phase change materials and the development of heat pumps, i.e. in any “Rational Use of Energy” agenda. Nearly 60% of dwellings in European countries are still single glazed causing excessive heat losses and hence increased carbon dioxide emissions. By upgrading glass U-values from 5.7 to 1.6 Wm-2K-1, the corresponding European CO2 reduction was estimated at 82 million tonnes per year. Vacuum glazing consists of two sheets of glass hermetically sealed around their periphery with a vacuum gap between the glass sheets. An array of tiny support pillars, typically 0.3–0.5 mm in diameter, are used to separate the glass panes and to prevent them from touching due to atmospheric pressure. Low emittance (low-e) coatings are used on one or both of the internal glass surfaces to reduce radiative heat transfer from the inside to the outside of the glazing. The University of Ulster has developed and patented a novel sealing technique for the fabrication of vacuum glazing at low temperatures and have fabricated glazing with a mid-pane U-values down to 0.86 Wm-2K-1 for a 0.4m by 0.4m sample employing hard low-e coatings.
Thermal Energy Storage (Dr P Griffiths):Energy in phase change materials (PCMs) allows very high energy densities to be achieved at well defined temperatures. Studies showing improvements in cooling of spaces through enhanced chilled beam ceilings and energy storage up to 65°C for heating applications have carried out. Also there has been activity in modelling and application of PCMs into building wall elements to create the effect of thermal mass to reduce cooling demands.
Advanced Heat Pumps (Professor NJ Hewitt):Heat pumps are increasing popular in Ireland and research is focussed on more efficient and cost-effective systems. Previous projects include new fluid development and evaluation and new system development. Current projects include the development of high temperature air-source heat pumps for domestic retrofit and the development of a combined compressor/expander unit to improve efficiency. Air-source heat pumps have an advantage in the moderate maritime climate of Ireland with its relatively warm winter conditions and avoid the expensive ground source installation. High temperature air-source systems with a seasonal coefficient of performance (heating) of over 3.0 have been developed and tested with the advantage that they can be retrofitted directly into existing wet radiator systems traditionally heated by a boiler.
For further information contact:
Professor Neil Hewitt
Centre for Sustainable Technologies
School of The Built Environment
University of Ulster
Tel: 44 (0)28 9036 8566