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Summertime cooling with ventilation radiators
KTH, School of Technology and Health (STH), Fluid and Climate Technology (closed 20090101).
KTH, School of Technology and Health (STH), Fluid and Climate Technology (closed 20090101).ORCID iD: 0000-0003-1882-3833
2007 (English)In: IAQVEC 2007 Proceedings - 6th International Conference on Indoor Air Quality, Ventilation and Energy Conservation in Buildings: Sustainable Built Environment, 2007, 533-538 p.Conference paper (Refereed)
Abstract [en]

Ventilation radiators, heat emitters where cold ventilation air is brought directly from outdoors into the room via heated radiator surfaces, are becoming more and more common in Scandinavia. Because these systems combine both heating and ventilation several interesting aspects arise that may be used to save energy and improve indoor thermal climate. The heating aspects in wintertime have been discussed in previous papers from KTH STH. This study investigates whether ventilation radiators may be used for cooling in summertime. Results from the study show that condensation of water is the main problem to tackle when ventilation radiators are used for cooling purposes. It is difficult to avoid condensation, especially inside the ventilation channel where incoming ventilation air comes into contact with chilled radiator surfaces. The problem increases with increased temperature difference between radiator surface and ventilation air. This is why ventilation radiators seem unsuitable for cooling in summertime without risking condensation of water. However, if condensation of water is allowed in the ventilation channel only, ventilation radiators may be functional for cooling. The trick is to find a way to drain water from the ventilation channel to avoid hygiene problems.

Place, publisher, year, edition, pages
2007. 533-538 p.
Keyword [en]
Condensation, Summertime cooling, Ventilation radiator
National Category
Other Civil Engineering
URN: urn:nbn:se:kth:diva-31936ScopusID: 2-s2.0-84857249147ISBN: 978-486163071-2OAI: diva2:407089
The 6th International Conference on Indoor Air Quality, Ventilation & Energy Conservation in Buildings IAQVEC 2007, Oct. 28 - 31 2007, Sendai, Japan

QC 20110328

Available from: 2011-03-29 Created: 2011-03-29 Last updated: 2014-10-27Bibliographically approved
In thesis
1. Potential of Ventilation Radiators: Performance evaluation by numerical, analytical and experimental means
Open this publication in new window or tab >>Potential of Ventilation Radiators: Performance evaluation by numerical, analytical and experimental means
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Energy consumption for heating and ventilation of buildings is still in 2011considered far too high, but there are many ways to save energy and construct lowenergy buildings that have not been fully utilised. This doctoral thesis has focused onone of these - low temperature heating systems. Particular attention has been given tothe ventilation radiator adapted for exhaust-ventilated buildings because of itspotential as a low energy consuming, easily-operated, environmentally-friendlysystem that might also ensure occupant health and well-being.

Investigations were based on Computational Fluid Dynamics (CFD) simulations andanalytical calculations, with laboratory experiments used for validation.

Main conclusions:

  • Low and very low temperature heating systems, such as floor heating, in general createan indoor climate with low air speeds and low temperature differences in the room, whichis beneficial for thermal comfort. A typical disadvantage, however, was found to beweakness in counteracting cold down-flow from ventilation air supply units in exhaustventilatedbuildings.
  • with ventilation radiators, unlike most other low temperature systems, it was found thatthe risk of cold draught could be reduced while still maintaining a high ventilation rateeven in cold northern European winters.
  • ventilation radiators were found to be more thermally efficient than traditional radiators.
  • design of ventilation radiators could be further modified for improved thermal efficiency.
  • at an outdoor temperature of -15 °C the most efficient models were able to give doublethe heat output of traditional radiators. Also, by substituting the most efficient ventilationradiators for traditional radiators operating at 55 °C supply water temperature, it wasfound that supply water temperature could be reduced to 35 °C while heat outputremained the same and comfort criteria were met.
  • lowering the supply water temperature by 20 °C (as described above) could givecombined energy savings for heating and ventilation of 14-30 % in a system utilising aheat pump.
  • supply water temperatures as low as 35 °C could increase potential for utilising lowtemperature heat sources such as sun-, ground-, water- or waste-heat. This would beparticularly relevant to new-built “green” energy-efficient buildings, but severaladvantages may apply to retrofit applications as well.
  • Successful application of ventilation radiators requires understanding of relevant buildingfactors, and the appropriate number, positioning and size of radiators for best effect.Evaluation studies must be made at the level of the building as a whole, not just for theheating-ventilation system.

This work demonstrated that increased use of well-designed ventilation radiatorarrangements can help to meet regulations issued in 2008 by the Swedish Departmentof Housing (Boverket BBR 16) and goals set in the Energy Performance of BuildingsDirective (EPBD) in the same year.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. 63 p.
Ventilation radiator, thermal comfort, exhaust ventilation, CFD, energy saving, convection fin, low temperature heating
National Category
Building Technologies
urn:nbn:se:kth:diva-31813 (URN)978-91-7415-940-0 (ISBN)
Public defence
2011-04-18, F3 (Flodis), Lindstedtsvägen 26,, 114 28 Stockholm, 16:12 (English)
STEM Projektnummer:30326-1 Energieffektiva lågtemperatursystem i byggnader
QC 20110328Available from: 2011-03-29 Created: 2011-03-25 Last updated: 2011-04-05Bibliographically approved

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