--- title: Why does humidity matter? description: Simply increasing ventilation rates to reduce indoor transmission of airborne viruses may not deliver the right result. image: https://blog.swegon.com/hubfs/AdobeStock_261256314.jpeg --- [![](https://www.swegon.com/Static/img/logo.svg?v=3)](https://www.swegon.com/uk/) Menu - [Solutions & services](https://www.swegon.com/uk/solutions-and-services/) - [Products>](https://www.swegon.com/uk/products/) - [References & Insights](https://www.swegon.com/uk/references-and-insights/) - [Support & Software](https://www.swegon.com/uk/support/) - [Sustainability](https://www.swegon.com/uk/sustainability/) - [Why Swegon?](https://www.swegon.com/uk/why-swegon/) - [Product Search](https://www.swegon.com/uk/product-search-result/) - [Document Search](https://www.swegon.com/uk/support/find-documents/) - [Careers](https://www.swegon.com/uk/careers/) - United Kingdom - [Contact](https://www.swegon.com/uk/contact/) ## Choose a market [Or visit our global site](https://www.swegon.com) - [Belgium - French](https://www.swegon.com/fr-be/) - [Belgium - Dutch](https://www.swegon.com/nl-be/) - [Denmark](https://www.swegon.com/da/) - [Finland](https://www.swegon.com/fi/) - [France](https://www.swegon.com/fr/) - [Italy](https://www.swegon.com/it/) - [Germany](https://www.swegon.com/de/) - [Norway](https://www.swegon.com/no/) - [Poland](https://www.swegon.com/pl/) - [Spain](https://www.swegon.com/es/) - [Sweden](https://www.swegon.com/sv/) - [Switzerland - German](https://www.swegon.com/de-ch/) - [Switzerland - French](https://www.swegon.com/fr-ch/) - [Switzerland - Italian](https://www.swegon.com/it-ch/) - [United Kingdom](https://www.swegon.com/uk/) - [United States](https://www.swegonnorthamerica.com) - [Canada](http://swegonnorthamerica.com/) Explore ## Filter articles ### By topics - [Cooling & Heating (40)](https://blog.swegon.com/uk/tag/cooling-heating) - [Indoor Climate Knowledge (22)](https://blog.swegon.com/uk/tag/indoor-climate-knowledge) - [Air Handling Units (20)](https://blog.swegon.com/uk/tag/air-handling-units) - [Smoke and Fire Dampers (19)](https://blog.swegon.com/uk/tag/smoke-and-fire-dampers) - [Room Units (18)](https://blog.swegon.com/uk/tag/room-units) - [Indoor Climate Knowledge (15)](https://blog.swegon.com/uk/tag/indoor-climate-knowledge) - [Energy Efficiency (13)](https://blog.swegon.com/uk/tag/energy-efficiency) - [News (13)](https://blog.swegon.com/uk/tag/news) - [Tips and Advice (13)](https://blog.swegon.com/uk/tag/tips-and-advice) - [sustainability (13)](https://blog.swegon.com/uk/tag/sustainability) - [Knowledge (11)](https://blog.swegon.com/uk/tag/knowledge) - [Ventilation (10)](https://blog.swegon.com/uk/tag/ventilation) - [Energy Efficiency (8)](https://blog.swegon.com/uk/tag/energy-efficiency) - [Service (7)](https://blog.swegon.com/uk/tag/service) - [Guide (5)](https://blog.swegon.com/uk/tag/guide) - [Humidity (5)](https://blog.swegon.com/uk/tag/humidity) - [Heat pumps (3)](https://blog.swegon.com/uk/tag/heat-pumps) - [BIM (2)](https://blog.swegon.com/uk/tag/bim) - [Diffusion (2)](https://blog.swegon.com/uk/tag/diffusion) - [Services & Connectivity (2)](https://blog.swegon.com/uk/tag/services-connectivity) - [acoustics (2)](https://blog.swegon.com/uk/tag/acoustics) > Fler ### By authors - [![Ajeeb Mohammed](https://blog.swegon.com/hs-fs/hubfs/IMG_20230113_160922.jpg?width=75&name=IMG_20230113_160922.jpg) Ajeeb Mohammed 1](https://blog.swegon.com/uk/author/ajeeb-mohammed) - [![Alberto Ferrandi](https://blog.swegon.com/hs-fs/hubfs/ferrandi.png?width=75&name=ferrandi.png) Alberto Ferrandi 5](https://blog.swegon.com/uk/author/alberto-ferrandi) - [![Alberto Frison](https://blog.swegon.com/hs-fs/hubfs/alberto.jpg?width=75&name=alberto.jpg) Alberto Frison 2](https://blog.swegon.com/uk/author/alberto-frison) - [![Alessandro Lora](https://blog.swegon.com/hs-fs/hubfs/lora.webp?width=75&name=lora.webp) Alessandro Lora 1](https://blog.swegon.com/uk/author/alessandro-lora) - [![Alessandro Lora](https://blog.swegon.com/hs-fs/hubfs/lora.webp?width=75&name=lora.webp) Alessandro Lora 1](https://blog.swegon.com/uk/author/alessandro-lora) - [![Alessandro Pinato](https://blog.swegon.com/hs-fs/hubfs/alessandro.png?width=75&name=alessandro.png) Alessandro Pinato 7](https://blog.swegon.com/uk/author/alessandro-pinato) - [![Anders de Maré](https://blog.swegon.com/hs-fs/hubfs/anders%20de%20mare_1-1.jpg?width=75&name=anders%20de%20mare_1-1.jpg) Anders de Maré 1](https://blog.swegon.com/uk/author/anders-de-maré) - [![Andreas Örje Wellstam](https://blog.swegon.com/hs-fs/hubfs/Finland%20News/Kampanjat,%20uutiskirjeet/Andreas%20%C3%96rje%20Wellstam_S.jpg?width=75&name=Andreas%20%C3%96rje%20Wellstam_S.jpg) Andreas Örje Wellstam 5](https://blog.swegon.com/uk/author/andreas-örje-wellstam) - [![Andrew Collard](https://blog.swegon.com/hs-fs/hubfs/Andrew%20Collard_edited.jpg?width=75&name=Andrew%20Collard_edited.jpg) Andrew Collard 2](https://blog.swegon.com/uk/author/andrew-collard) - [![Andy Bott](https://blog.swegon.com/hs-fs/hubfs/me.jpg?width=75&name=me.jpg) Andy Bott 1](https://blog.swegon.com/uk/author/andy-bott) - [![Andy Dines](https://blog.swegon.com/hs-fs/hubfs/Swegon%20UKI/20260519_095206.jpg?width=75&name=20260519_095206.jpg) Andy Dines 1](https://blog.swegon.com/uk/author/andy-dines) - [![Börje Lehrman](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/SE-SV%20-%20PRO%20-%20BACV/B%C3%B6rje_Lehrman.jpg?width=75&name=B%C3%B6rje_Lehrman.jpg) Börje Lehrman 1](https://blog.swegon.com/uk/author/börje-lehrman-1) - [![Carinne Grandjean](https://blog.swegon.com/hs-fs/hubfs/carinneg.webp?width=75&name=carinneg.webp) Carinne Grandjean 1](https://blog.swegon.com/uk/author/carinne-grandjean) - [![Carl-Ola Danielsson](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/1494416201_4f37bc2792.jpg?width=75&name=1494416201_4f37bc2792.jpg) Carl-Ola Danielsson 3](https://blog.swegon.com/uk/author/carl-ola-danielsson) - [![Carl-Ola Danielsson](https://blog.swegon.com/hs-fs/hubfs/Carl%20Ola%20Danielsson.png?width=75&name=Carl%20Ola%20Danielsson.png) Carl-Ola Danielsson 3](https://blog.swegon.com/uk/author/carl-ola-danielsson) - [![Caroline Jacobsson](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/Caroline%20Jacobsson.jpg?width=75&name=Caroline%20Jacobsson.jpg) Caroline Jacobsson 13](https://blog.swegon.com/uk/author/caroline-jacobsson) - [![Caroline Jacobsson](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/Caroline%20Jacobsson.jpg?width=75&name=Caroline%20Jacobsson.jpg) Caroline Jacobsson 13](https://blog.swegon.com/uk/author/caroline-jacobsson) - [![Christoffer Lindström](https://blog.swegon.com/hs-fs/hubfs/Christoffer_blogg.png?width=75&name=Christoffer_blogg.png) Christoffer Lindström 2](https://blog.swegon.com/uk/author/christoffer-lindström) - [![Dan Jones](https://blog.swegon.com/hs-fs/hubfs/dan_jones.jpg?width=75&name=dan_jones.jpg) Dan Jones 2](https://blog.swegon.com/uk/author/dan-jones) - [![Darren Peel](https://blog.swegon.com/hs-fs/hubfs/Darren.jpg?width=75&name=Darren.jpg) Darren Peel 1](https://blog.swegon.com/uk/author/darren-peel) - [![Dave Harding](https://blog.swegon.com/hs-fs/hubfs/dave_harding.jpg?width=75&name=dave_harding.jpg) Dave Harding 2](https://blog.swegon.com/uk/author/david-harding) - [![Dene Kent](https://blog.swegon.com/hs-fs/hubfs/Dene%20Kent%20Swegon.jpg?width=75&name=Dene%20Kent%20Swegon.jpg) Dene Kent 6](https://blog.swegon.com/uk/author/dene-kent) - [![Elvis Kokot](https://blog.swegon.com/hs-fs/hubfs/elviskokot.png?width=75&name=elviskokot.png) Elvis Kokot 1](https://blog.swegon.com/uk/author/elvis-kokot) - [![Fabio Polo](https://blog.swegon.com/hs-fs/hubfs/Fabio%20Polo-1.jpg?width=75&name=Fabio%20Polo-1.jpg) Fabio Polo 7](https://blog.swegon.com/uk/author/fabio-polo) - [![Fabio Polo](https://blog.swegon.com/hs-fs/hubfs/Fabio%20Polo-1.jpg?width=75&name=Fabio%20Polo-1.jpg) Fabio Polo 7](https://blog.swegon.com/uk/author/fabio-polo) - [![Federica Serena](https://blog.swegon.com/hs-fs/hubfs/Serena.webp?width=75&name=Serena.webp) Federica Serena 2](https://blog.swegon.com/uk/author/federica-serena) - [![Francesco Artusi](https://blog.swegon.com/hs-fs/hubfs/Francesco%20Artusi%20CUT.jpg?width=75&name=Francesco%20Artusi%20CUT.jpg) Francesco Artusi 1](https://blog.swegon.com/uk/author/francesco-artusi) - [Frank Schönfelder 2](https://blog.swegon.com/uk/author/frank-schönfelder) - [![François Jouvray](https://blog.swegon.com/hs-fs/hubfs/Fran%C3%A7ois%20Jouvray%20swegon.jpg?width=75&name=Fran%C3%A7ois%20Jouvray%20swegon.jpg) François Jouvray 1](https://blog.swegon.com/uk/author/françois-jouvray) - [![Hannah Finning](https://blog.swegon.com/hs-fs/hubfs/Image%20(5).jpg?width=75&name=Image%20(5).jpg) Hannah Finning 1](https://blog.swegon.com/uk/author/hannah-finning) - [![James Moore](https://blog.swegon.com/hs-fs/hubfs/download.jpg?width=75&name=download.jpg) James Moore 1](https://blog.swegon.com/uk/author/james-moore) - [![Jan Scheuring](https://blog.swegon.com/hs-fs/hubfs/Photo_Jan-1.jpeg?width=75&name=Photo_Jan-1.jpeg) Jan Scheuring 1](https://blog.swegon.com/uk/author/jan-scheuring) - [![Jim Collings](https://blog.swegon.com/hs-fs/hubfs/Swegon%20UKI/Jim%20Collings.jpeg?width=75&name=Jim%20Collings.jpeg) Jim Collings 1](https://blog.swegon.com/uk/author/jim-collings) - [![John Lindblom](https://blog.swegon.com/hs-fs/hubfs/johnl.png?width=75&name=johnl.png) John Lindblom 1](https://blog.swegon.com/uk/author/john-lindblom) - [![John Wibrand](https://blog.swegon.com/hs-fs/hubfs/John%20Wibrand.jpg?width=75&name=John%20Wibrand.jpg) John Wibrand 2](https://blog.swegon.com/uk/author/john-wibrand) - [![John Wibrand](https://blog.swegon.com/hs-fs/hubfs/John%20Wibrand.jpg?width=75&name=John%20Wibrand.jpg) John Wibrand 2](https://blog.swegon.com/uk/author/john-wibrand) - [![Josh Emerson](https://blog.swegon.com/hs-fs/hubfs/Josh_Emerson_Headshot.jpg?width=75&name=Josh_Emerson_Headshot.jpg) Josh Emerson 4](https://blog.swegon.com/uk/author/josh-emerson) - [![Josh Emerson](https://blog.swegon.com/hs-fs/hubfs/Josh_Emerson_Headshot.jpg?width=75&name=Josh_Emerson_Headshot.jpg) Josh Emerson 4](https://blog.swegon.com/uk/author/josh-emerson) - [![Luca Filippetto](https://blog.swegon.com/hs-fs/hubfs/Luca%20Filippetto%20Hubspot.jpg?width=75&name=Luca%20Filippetto%20Hubspot.jpg) Luca Filippetto 2](https://blog.swegon.com/uk/author/luca-filippetto) - [![Luca Zordan](https://blog.swegon.com/hs-fs/hubfs/lucazordan.png?width=75&name=lucazordan.png) Luca Zordan 1](https://blog.swegon.com/uk/author/luca-zordan-1) - [![Magnus Andersson](https://blog.swegon.com/hs-fs/hubfs/magnus%20andersson_550x550%20(1).jpg?width=75&name=magnus%20andersson_550x550%20(1).jpg) Magnus Andersson 1](https://blog.swegon.com/uk/author/magnus-andersson) - [![Malin Höij](https://blog.swegon.com/hs-fs/hubfs/malinh.webp?width=75&name=malinh.webp) Malin Höij 2](https://blog.swegon.com/uk/author/malin-höij) - [![Malin Höij](https://blog.swegon.com/hs-fs/hubfs/malinh.webp?width=75&name=malinh.webp) Malin Höij 2](https://blog.swegon.com/uk/author/malin-höij) - [![Markku Palola](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/Markku_Palola_50x83.jpg?width=75&name=Markku_Palola_50x83.jpg) Markku Palola 1](https://blog.swegon.com/uk/author/markku-palola) - [![Markus Schomaker](https://blog.swegon.com/hs-fs/hubfs/Swegon%20UKI/Markus%20Schomaker.jpg?width=75&name=Markus%20Schomaker.jpg) Markus Schomaker 1](https://blog.swegon.com/uk/author/markus-schomaker) - [![Martin Brady](https://blog.swegon.com/hs-fs/hubfs/1569580194632.jpg?width=75&name=1569580194632.jpg) Martin Brady 1](https://blog.swegon.com/uk/author/martin-brady) - [![Martin Ottersten](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/Martin_Ottersten.jpg?width=75&name=Martin_Ottersten.jpg) Martin Ottersten 2](https://blog.swegon.com/uk/author/martin-ottersten) - [![Martin Ottersten](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/Martin_Ottersten.jpg?width=75&name=Martin_Ottersten.jpg) Martin Ottersten 2](https://blog.swegon.com/uk/author/martin-ottersten) - [![Martin Procter](https://blog.swegon.com/hs-fs/hubfs/MP.jpg?width=75&name=MP.jpg) Martin Procter 2](https://blog.swegon.com/uk/author/martin-procter) - [![Michael Ward](https://blog.swegon.com/hs-fs/hubfs/Michael_Ward_photo.jpg?width=75&name=Michael_Ward_photo.jpg) Michael Ward 1](https://blog.swegon.com/uk/author/michael-ward) - [![Mikael Börjesson](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/Mikael%20B%C3%B6rjesson.jpg?width=75&name=Mikael%20B%C3%B6rjesson.jpg) Mikael Börjesson 10](https://blog.swegon.com/uk/author/mikael-börjesson) - [![Mikael Börjesson](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/Mikael%20B%C3%B6rjesson.jpg?width=75&name=Mikael%20B%C3%B6rjesson.jpg) Mikael Börjesson 10](https://blog.swegon.com/uk/author/mikael-börjesson) - [![Mike Ward](https://blog.swegon.com/hs-fs/hubfs/Michael_Ward_photo.jpg?width=75&name=Michael_Ward_photo.jpg) Mike Ward 4](https://blog.swegon.com/uk/author/mike-ward) - [![Mirko Sauvan](https://blog.swegon.com/hs-fs/hubfs/Swegon_Mirko%20Sauvan_web_3.jpg?width=75&name=Swegon_Mirko%20Sauvan_web_3.jpg) Mirko Sauvan 2](https://blog.swegon.com/uk/author/mirko-sauvan-1) - [![Morten von Sydow](https://blog.swegon.com/hs-fs/hubfs/Morten.jpg?width=75&name=Morten.jpg) Morten von Sydow 1](https://blog.swegon.com/uk/author/morten-von-sydow) - [![Niklas Jacobsson](https://blog.swegon.com/hs-fs/hubfs/authorniklas.png?width=75&name=authorniklas.png) Niklas Jacobsson 2](https://blog.swegon.com/uk/author/niklas-jacobsson) - [![Owen Crawford](https://blog.swegon.com/hs-fs/hubfs/0%20(1).jpg?width=75&name=0%20(1).jpg) Owen Crawford 1](https://blog.swegon.com/uk/author/owen-crawford) - [![Paola Moschini (Guest author)](https://blog.swegon.com/hs-fs/hubfs/forfattare.png?width=75&name=forfattare.png) Paola Moschini (Guest author) 1](https://blog.swegon.com/uk/author/paola-moschini) - [![Paolo Dalle Fratte](https://blog.swegon.com/hs-fs/hubfs/Paolo%20profile%20image.jpg?width=75&name=Paolo%20profile%20image.jpg) Paolo Dalle Fratte 1](https://blog.swegon.com/uk/author/paolo-dalle-fratte) - [![Per-Åke Ottemark](https://blog.swegon.com/hs-fs/hubfs/1521139778203.jpg?width=75&name=1521139778203.jpg) Per-Åke Ottemark 1](https://blog.swegon.com/uk/author/per-âke-ottemark) - [![Peter Faruqi Nicholas](https://blog.swegon.com/hs-fs/hubfs/Peter%20Faruqi.jpg?width=75&name=Peter%20Faruqi.jpg) Peter Faruqi Nicholas 2](https://blog.swegon.com/uk/author/peter-faruqi-nicholas) - [![Philip Andersson](https://blog.swegon.com/hs-fs/hubfs/Philip_Andersson_pressbild_small_webb.jpg?width=75&name=Philip_Andersson_pressbild_small_webb.jpg) Philip Andersson 1](https://blog.swegon.com/uk/author/philip-andersson) - [![Robert Flaherty](https://blog.swegon.com/hs-fs/hubfs/RF%20photo.jpg?width=75&name=RF%20photo.jpg) Robert Flaherty 1](https://blog.swegon.com/uk/author/robert-flaherty) - [![Robert Siverby](https://blog.swegon.com/hs-fs/hubfs/MicrosoftTeams-image%20(3)-4.png?width=75&name=MicrosoftTeams-image%20(3)-4.png) Robert Siverby 1](https://blog.swegon.com/uk/author/robert-siverby) - [![Ryan Fossey](https://blog.swegon.com/hs-fs/hubfs/Swegon%20UKI/Personal%20photo%201.jpg?width=75&name=Personal%20photo%201.jpg) Ryan Fossey 2](https://blog.swegon.com/uk/author/ryan-fossey) - [![Shannon Jezzard](https://blog.swegon.com/hubfs/1564654168812.jfif) Shannon Jezzard 3](https://blog.swegon.com/uk/author/shannon-jezzard) - [![Stefan Lay](https://blog.swegon.com/hs-fs/hubfs/1517033472060.jpg?width=75&name=1517033472060.jpg) Stefan Lay 6](https://blog.swegon.com/uk/author/stefan-lay) - [![Steve Gore](https://blog.swegon.com/hs-fs/hubfs/1516820800199.jpg?width=75&name=1516820800199.jpg) Steve Gore 10](https://blog.swegon.com/uk/author/steve-gore) - [![Swegon](https://blog.swegon.com/hs-fs/hubfs/LinkedinSwegonlogo-1.jpg?width=75&name=LinkedinSwegonlogo-1.jpg) Swegon 10](https://blog.swegon.com/uk/author/swegon-0) - [Swegon Air Academy 2](https://blog.swegon.com/uk/author/swegon-air-academy) - [Eur Ing Professor Tim Dwyer 2](https://blog.swegon.com/uk/author/tim-dwyer) - [![Timo Schreck](https://blog.swegon.com/hs-fs/hubfs/Timo%20Schreck.jpg?width=75&name=Timo%20Schreck.jpg) Timo Schreck 2](https://blog.swegon.com/uk/author/timo-schreck) - [![Tobias Nordström](https://blog.swegon.com/hs-fs/hubfs/TobiasNordstromPHOTO.jpg?width=75&name=TobiasNordstromPHOTO.jpg) Tobias Nordström 2](https://blog.swegon.com/uk/author/tobias-nordström) - [![Toby Young](https://blog.swegon.com/hs-fs/hubfs/Image2.jpeg?width=75&name=Image2.jpeg) Toby Young 1](https://blog.swegon.com/uk/author/toby-young) - [![Tony Olsson](https://blog.swegon.com/hs-fs/hubfs/Tony%20Olsson.webp?width=75&name=Tony%20Olsson.webp) Tony Olsson 5](https://blog.swegon.com/uk/author/tony-olsson) - [![Tony Olsson](https://blog.swegon.com/hs-fs/hubfs/Tony%20Olsson.webp?width=75&name=Tony%20Olsson.webp) Tony Olsson 5](https://blog.swegon.com/uk/author/tony-olsson) - [![Tony Pettersson](https://blog.swegon.com/hs-fs/hubfs/tonyp.jpg?width=75&name=tonyp.jpg) Tony Pettersson 1](https://blog.swegon.com/uk/author/tony-pettersson) - [![Welat Han](https://blog.swegon.com/hs-fs/hubfs/Welat%20Han.jpg?width=75&name=Welat%20Han.jpg) Welat Han 3](https://blog.swegon.com/uk/author/welat-han) - [![William Lawrance](https://blog.swegon.com/hs-fs/hubfs/William_lawrance.jpg?width=75&name=William_lawrance.jpg) William Lawrance 5](https://blog.swegon.com/uk/author/william-lawrance) - [![William Lawrance](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/SE-SV%20-%20PRO%20-%20BACV/William%20Lawrance.jpg?width=75&name=William%20Lawrance.jpg) William Lawrance 5](https://blog.swegon.com/uk/author/william-lawrance) - [![Åsa Norén-Lundh](https://blog.swegon.com/hs-fs/hubfs/A%CC%8Asa%20Nore%CC%81n-Lundh.webp?width=75&name=A%CC%8Asa%20Nore%CC%81n-Lundh.webp) Åsa Norén-Lundh 4](https://blog.swegon.com/uk/author/åsa-norén-lundh) - [![Åsa Norén-Lundh](https://blog.swegon.com/hs-fs/hubfs/Blog%20Authors/SE-SV%20-%20PRO%20-%20BACV/%C3%85sa%20Nor%C3%A9n-Lundh.png?width=75&name=%C3%85sa%20Nor%C3%A9n-Lundh.png) Åsa Norén-Lundh 4](https://blog.swegon.com/uk/author/åsa-norén-lundh) - [![Åsa Norén-Lundh](https://blog.swegon.com/hs-fs/hubfs/AsaLN.jpg?width=75&name=AsaLN.jpg) Åsa Norén-Lundh 1](https://blog.swegon.com/uk/author/åsa-norén-lundh-1) Explore - - - [All About Indoor Climate](https://blog.swegon.com/uk?hsLang=en-gb) Subscribe Share - - - Explore Share Subscribe [« go back](https://blog.swegon.com/uk) # Why does humidity matter? [Josh Emerson](https://blog.swegon.com/uk/author/josh-emerson) Mar 18, 2021 Simply increasing ventilation rates to reduce indoor transmission of airborne viruses may not deliver the right result. The Covid-19 crisis has thrust the work of building services engineers into the public eye and placed the effectiveness of ventilation systems, in particular, under close scrutiny. However, while the general public may now have a better idea of why controlled, mechanical ventilation is important to maintain healthy indoor conditions, the focus on increasing air change rates has rather over-simplified the message. Faced with rising rates of indoor transmission, the government and most industry bodies issued advice focused primarily on increasing ventilation rates to achieve minimum air changes of eight litres per second per person. Keeping CO2 concentrations below 800 parts per million was also recommended as an indicator of ventilation effectiveness. However, the importance of controlling relative humidity (RH) was somewhat overlooked despite it having been recognised as a key factor in achieving healthy indoor environments for many years. Fortunately, several leading healthcare experts have now started speaking up about this oversight. Dr Stephanie Taylor from Harvard Medical School believes control of RH is key to tackling Covid-19 and in preparing buildings for future health challenges. She told last year’s BESA National Conference that managing the indoor environment was “the best medicine for treatment and prevention” and building professionals were, therefore, the “physicians of the future”. The ASHRAE Distinguished Lecturer said numerous studies had identified an RH ‘sweet spot’ between 40% and 60% adding that air which was too dry would allow viruses to thrive and be more active. ## **Balance** She added that RH should not be sacrificed to reduce energy use. “We need to get that balance right.” The body of scientists advising the UK government during the pandemic has also made the link between RH and the welfare of building occupants. The Scientific Advisory Group for Emergencies (SAGE) said mitigating the risk of viral transmission through the air is not simply a case of increasing ventilation rates. Cath Noakes, Professor of Environmental Engineering for Buildings at the University of Leeds, one of two engineer members of SAGE, confirmed that studies had shown the risk was higher indoors when ventilation provided less than 3 l/s per person and that household transmission was a particular concern. However, she also said the virus thrived in “cool, dry and dark conditions”. However, current building standards still focus on a simple linear relationship between the outdoor temperature and indoor comfort temperature and there is no mandatory legal requirement to control RH. One positive outcome from the current crisis would be a long overdue change in this area because recommending high ventilation rates without counterbalancing that with RH control can lead to very dry indoor environments, which could have the perverse effect of creating conditions that actually help viruses thrive. In the cold, dry winters of northern Europe, indoor RH-levels can drop to 5-15% for extended periods, which is great for viruses, but not so good for people. If the humidity is too low, small particles are also more likely to be inhaled deep into lungs and infectious particles survive longer. If the RH remains below 30%, the skin becomes dry leading to itching, cracking and chapping. On the other hand if the humidity is too high, it encourages mould growth and bacteria that can cause respiratory problems and/or allergic reactions, including increasing the risk of asthma attacks. Very moist air will make people feel chilled in cold weather and hot and sticky in summer. Humidity also affects the performance of buildings, the durability of building envelope materials and the longevity of equipment. Basically, we need to control humidity so levels are not too low, and not too high. The moisture holding capacity of air increases dramatically with increases in temperature so, counter-intuitive though it might sound, it is often more economic to raise the air temperature because the increased moisture transport capacity will outweigh the increased energy consumption. We should also start to consider humidity as an asset and recover it in the same way we do thermal energy to help maintain healthy conditions without paying an energy penalty. Achieving the right RH for each space will depend on finding a balance that brings together all aspects of HVAC systems – including passive and active ventilation – to deliver healthy air change rates alongside the right temperature balance. It is a complex area, but today’s system designers have all the tools at their disposal – they just have to make the right calculations. *For an in-depth analysis of the humidity issues related to buildings and ways to deliver ideal RH download our humidity white paper at [here](https://blog.swegon.com/hubfs/Swegon.white.paper.humidity.pdf?utm_source=Blog&utm_medium=Downloads&utm_campaign=Humidity&hsLang=en-gb).* Topics: - [Humidity](https://blog.swegon.com/uk/tag/humidity) - - - [![Josh Emerson](https://blog.swegon.com/hs-fs/hubfs/Josh_Emerson_Headshot.jpg?width=200&name=Josh_Emerson_Headshot.jpg)](https://blog.swegon.com/uk/author/josh-emerson) [Josh Emerson](https://blog.swegon.com/uk/author/josh-emerson) Josh Emerson is the Marketing & Sales Development Director at Swegon UK&I. He is dedicated to advancing building efficiency and occupant well-being and his passion lies in creating sustainable and health-focused indoor environments, contributing to the broader mission of shaping a better built environment for all. ## Recommended reading - [Humidity](https://blog.swegon.com/uk/tag/humidity) ### [Timo Schreck](https://blog.swegon.com/uk/author/timo-schreck) ## [Relative humidity in the indoor air – impact on indoor air quality](https://blog.swegon.com/uk/relative-humidity-in-the-indoor-air-impact-on-indoor-air-quality?hsLang=en-gb) Indoor air humidity is often associated with various problems and … - [Humidity](https://blog.swegon.com/uk/tag/humidity) ### [Timo Schreck](https://blog.swegon.com/uk/author/timo-schreck) ## [Clearing up a few myths in humidity recovery](https://blog.swegon.com/uk/clearing-up-a-few-myths-in-humidity-recovery?hsLang=en-gb) There are many assumptions and opinions circulating around humidity … - [Air Handling Units](https://blog.swegon.com/uk/tag/air-handling-units) - [Humidity](https://blog.swegon.com/uk/tag/humidity) ### [William Lawrance](https://blog.swegon.com/uk/author/william-lawrance) ## [The many advantages of sorption technology](https://blog.swegon.com/uk/the-many-advantages-of-sorption-technology?hsLang=en-gb) Air handling units equipped with rotary heat exchangers with a … Get updates from the blog directly to your inbox. #### Get to know us - [Why Swegon?](https://www.swegon.com/uk/why-swegon/) - [Solutions & services](https://www.swegon.com/uk/solutions-and-services/) - [Products](https://www.swegon.com/uk/products/) - [References & Insights](https://www.swegon.com/uk/references-and-insights/) - [Support & Software](https://www.swegon.com/uk/support/) - [BlueBox Chiller ERP](http://www.blueboxcooling.com/) - [Sustainability](https://www.swegon.com/uk/sustainability/) #### More Swegon - [About us](https://www.swegon.com/uk/about-swegon/) - [Our Brands](https://www.swegon.com/uk/about-swegon/our-brands/) - [Contact](https://www.swegon.com/uk/contact/) - [Careers](https://www.swegon.com/uk/careers/) - [Information for suppliers](https://www.swegon.com/uk/contact/suppliers/) - [Swegon Designer Suite](https://sds.swegon.com/) - [Swegon Air Academy](https://www.swegonairacademy.com/en/) #### Subscribe to our blog [![](https://www.swegon.com/siteassets/logos/swegon-logo-white.svg)](https://www.swegon.com/uk/) Swegon Ltd, 5 Charterpoint Way, Ashby-de-la-Zouch Leicestershire LE65 1NF - [Privacy statement](https://www.swegon.com/uk/privacy-policy/) - [Cookies](https://www.swegon.com/uk/cookies/) - [Processing personal data](https://www.swegon.com/uk/privacy-policy/processing-personal-data/) - [Vulnerability disclosure policy](https://www.swegon.com/uk/vulnerability-disclosure-policy/) - [![Youtube](https://www.swegon.com/Static/img/youtube.svg)](https://www.youtube.com/user/SwegonAB) - [![Linkedin](https://www.swegon.com/Static/img/linkedin.svg)](https://www.linkedin.com/company/swegon-ab/) - [![Facebook](https://www.swegon.com/Static/img/facebook.svg)](https://www.facebook.com/swegongroup)