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Klimatundersökning i krypgrund: Mätning och simulering av temperatur och fukthalt
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
2014 (Swedish)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Climate Study in a Crawl Space : Measurement and Simulation of Temperature and Moisture Content (English)
Abstract [sv]

Köket på centralsjukhuset i Karlstad har byggts om. Efteråt har fuktproblem lokaliserats i vissa delar av krypgrundens tak under köket. Landstingsfastigheter, som sköter lokalerna, är intresserade av att få bort fukten samt undersöka hur klimatet i krypgrunden skulle förändras vid eventuella åtgärder med detta syfte.

Genom mätningar av temperaturer och fuktighet på olika platser i krypgrunden har klimatet fastställs. De mätningar som gjordes momentant var yttemperaturer på krypgrundens golv och tak samt kökets golv. Även luftens hastighet i krypgrunden mättes. Under en tvåveckorsperiod loggades även lufttemperatur och relativ luftfuktighet i krypgrunden.

Data från mätningarna användes sedan som indata då modeller byggdes i simuleringsprogrammet COMSOL. I COMSOL gjordes tre tvärsnitt i 2D över krypgrunden. Två 3D-modeller under ett av de områdena som drabbats av fuktproblem modellerades också. Med hjälp av modellerna simulerades hur tre olika fall av isolering; fem respektive tio cm jämt fördelat isolering samt välvd isolering, i krypgrundens tak vid de problematiska områdena skulle påverka klimatet i krypgrunden. Som alternativ till isolering provades också att simulera flänsar i taket med syftet att leda upp värme från luften till taket.

Mätningarna visade att krypgrunden håller en jämn temperatur även då temperaturen utomhus varierar. Idag håller krypgrunden en medeltemperatur på 16,8°C och luften har en medelhastighet på 0,046 m/s.

Analys av fuktigheten i grunden visar att fukten troligtvis inte kommer utifrån utan istället från sanden som utgör grundens golv. För att undvika kondensationsproblem i grunden bör temperaturen inte underskrida 13,1°C.

Simuleringarna visade att tilläggsisolering är ett bra alternativ för att höja taktemperaturen i de fuktdrabbade områdena. Isoleringen sänkte också medelhastigheten hos luften, vilket gör det enklare att kontrollera fukthalten i krypgrunden. Mest effektivt var det med välvd isolering.

Abstract [en]

After reconstruction of the kitchen at the Central Hospital in Karlstad, moisture problems were detected in certain parts of ceiling of the crawl space under the kitchen. Landstingsfastigheter, who manages the premises, was interested in removing the moisture and how the climate of the crawl space would change in the event of measures to this end.

Through measurements of temperature and humidity at different locations in the crawl space, the climate in the crawl space was determined. The measurements that were made were instantaneous surface temperatures of the floor and ceiling of the crawl space and the kitchen floor, as well as the movement of air in the crawl space. During a two-week period the air temperature and relative humidity in the crawl space was logged.

Data from the measurements were then used as input data for the models, which were built in the simulation software COMSOL. In COMSOL three cross-sections of the crawl space were made in 2D. Two 3D models describing the properties of the crawl space in one of the areas affected by the moisture were also made. The models were used to simulate the effect of five and ten cm of insulation, respectively, as well as how arched insulation in the roof of the crawl space in the problem areas would affect the climate of the crawl space. As an alternative to insulation flanges in the roof were also simulated, with the aim to transfer heat to the ceiling from the air.

The measurements showed that the crawl space temperature was maintained even when the outdoor temperature varied. Today the average temperature in the crawl space is 16.8°C and the average air movement is 0.046 m/s.

Analysis of the humidity in the crawl space shows that the moisture probably doesn’t enter the crawl space from the outside, but rather from the sand that makes up the ground floor. To avoid condensation problems in the crawl space all temperatures should exceed 13.1°C.

The simulations showed that adding insulation is a good option for raising the ceiling temperature in the areas affected by moisture. The insulation also lowered the average air movement, making it easier to control the moisture content in the crawl space. The most effective way to insulate the ceiling was to use arched insulation.

Place, publisher, year, edition, pages
2014.
National Category
Environmental Analysis and Construction Information Technology
Identifiers
URN: urn:nbn:se:kau:diva-32811OAI: oai:DiVA.org:kau-32811DiVA, id: diva2:727916
Educational program
Engineering: Energy and Environmental Engineering (300 ECTS credits)
Supervisors
Examiners
Available from: 2014-06-24 Created: 2014-06-23 Last updated: 2014-06-24Bibliographically approved

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