Change search
ReferencesLink to record
Permanent link

Direct link
Age of air and air exchange efficiency in idealized city models
KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
2009 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 44, no 8, 1714-1723 p.Article in journal (Refereed) Published
Abstract [en]

Wind can provide relevantly clean external (rural) air into urban street network, i.e. city ventilation. The local mean age of air denotes the time it takes for the external air to reach a location after entering the urban canopy layer. The air exchange efficiency denotes the efficiency of flushing the street network with external air. However, difficulties exist in calculating the local mean age of air in a city due to open boundaries. The traditional experimental homogeneous emission method is adapted here in a CFD method to predict the urban local age of air and analyze the air exchange efficiency for city ventilation. Three simple city models are considered, including a round city model, a square city model and a long rectangular city with one main street parallel to the approaching wind or with two crossing streets. The difference in the city shape results in significant difference in the local mean age of air. In the round city of one narrow street, two inflows through street openings converge close to the city centre and exits through the street roof, so the air close to the city centre is relatively old and the air exchange efficiency is low (30%). For a round city with two crossing streets, a slightly non-parallel wind to the main street generates younger air and the higher air exchange efficiency in the city.

Place, publisher, year, edition, pages
2009. Vol. 44, no 8, 1714-1723 p.
Keyword [en]
Urban morphology, CFD, Local mean age of air, Homogeneous emission method, Air exchange efficiency
National Category
Civil Engineering
URN: urn:nbn:se:kth:diva-32356DOI: 10.1016/j.buildenv.2008.11.013ISI: 000265171300019ScopusID: 2-s2.0-61749103944OAI: diva2:410626
QC 20110414Available from: 2011-04-14 Created: 2011-04-13 Last updated: 2011-04-14Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Sandberg, Mats
By organisation
Energy Technology
In the same journal
Building and Environment
Civil Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 40 hits
ReferencesLink to record
Permanent link

Direct link