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Energy savings and thermal comfort with ventilation radiators: a dynamic heating and ventilation system
KTH, School of Technology and Health (STH), Fluid and Climate Technology.
KTH, School of Technology and Health (STH), Fluid and Climate Technology.ORCID iD: 0000-0003-1882-3833
2007 (English)In: Proceedings of Clima 2007 WellBeing Indoors, 2007Conference paper, Published paper (Other academic)
Abstract [en]

Studies indicate that a high ventilation rate with fresh air supply directly from outdoors gives better thermal comfort conditions, less SBS (Sick Building Syndrome) symptoms and increased work productivity. The drawbacks with a high ventilation rate in natural or exhaust ventilated buildings are normally increased energy use for heating and cold air draught. Such problems may be minimized with ventilation radiators, radiators where cold ventilation air is brought directly from outdoors through a wall channel into the radiator where it is heated before entering the room.

This paper discusses advantages with ventilation radiators in comparison to those of traditional heating systems. Focus has been on energy aspects and thermal comfort. The main conclusions are that ventilation radiators may give a stable and uniform thermal indoor climate. The high thermal gradient between cold ventilation air and the radiator surface inside the ventilation channel also makes the ventilation radiator more efficient than other systems. A method to vary indoor climate on a daily basis according to where people stay is proposed for additional energy savings with ventilation radiators. The deductions were based on results from CFD simulations in a well validated office model.

Place, publisher, year, edition, pages
2007.
Keywords [en]
Ventilation radiator, CFD, thermal comfort, energy consumption
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:kth:diva-8216OAI: oai:DiVA.org:kth-8216DiVA, id: diva2:13476
Conference
Clima 2007, 10-14 June, Helsinki, Finland
Note
QC 20101118Available from: 2008-04-09 Created: 2008-04-09 Last updated: 2011-03-29Bibliographically approved
In thesis
1. Low temperature heating in exhaust ventilated rooms: An approach using Computational Fluid Dynamics
Open this publication in new window or tab >>Low temperature heating in exhaust ventilated rooms: An approach using Computational Fluid Dynamics
2008 (English)Licentiate thesis, comprehensive summary (Other scientific)
Place, publisher, year, edition, pages
Stockholm: KTH, 2008. p. 27
Series
Trita-STH : report, ISSN 1653-3836 ; 2008:4
National Category
Building Technologies
Identifiers
urn:nbn:se:kth:diva-4694 (URN)978-91-7178-948-8 (ISBN)
Presentation
2008-04-28, Sal 5093, Riksäpplet 2, Campus Haninge, 10:00
Opponent
Supervisors
Note
QC 20101118Available from: 2008-04-09 Created: 2008-04-09 Last updated: 2010-11-18Bibliographically approved
2. 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. p. 63
Keywords
Ventilation radiator, thermal comfort, exhaust ventilation, CFD, energy saving, convection fin, low temperature heating
National Category
Building Technologies
Identifiers
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)
Opponent
Supervisors
Projects
STEM Projektnummer:30326-1 Energieffektiva lågtemperatursystem i byggnader
Note
QC 20110328Available from: 2011-03-29 Created: 2011-03-25 Last updated: 2011-04-05Bibliographically approved

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