magistrsko delo
Tanja Buh (Author), Janja Vaupotič (Mentor), Mateja Dovjak (Mentor)

Abstract

Radon (222Rn) je naravni radioaktivni plin, ki ob daljši izpostavljenosti pri človeku poveča tveganje za nastanek pljučnega raka. V stavbe vstopa 222Rn preko stavbnega ovoja, ki je v stiku z zemljino, zato je njegova koncentracija v zraku stavb odvisna od koncentracije v talnem zraku, kakovosti gradnje, meteoroloških dejavnikov in prezračevanja (naravno ali mehansko). Za raziskavo smo izbrali dve sosednji stanovanjski stavbi: (i) novejšo naseljeno z dobro zrakotesnostjo stavbnega ovoja in (ii) starejšo nenaseljeno s slabšo zrakotesnostjo stavbnega ovoja. V obeh stavbah smo v obdobju april–december 2021 merili koncentracije 222Rn, v novejši stavbi pa smo s pomočjo simulacije optimizirali prezračevanje. Najprej smo izvedli tridnevne (tj. kratkotrajne) kontinuirne meritve koncentracije 222Rn v izbranih prostorih obeh stavb. Na osnovi rezultatov smo izbrali prostore za nadaljnje meritve, in sicer v novejši (študentsko sobo, dnevno sobo in klet) in v starejši stavbi (kopalnico), kjer smo izvedli večtedenske (t.i. dolgotrajne) kontinuirne meritve koncentracije 222Rn v vseh letnih časih. Ugotovili smo, da so povprečne letne koncentracije 222Rn v novejši stavbi pod referenčno mejo 300 Bq/m3 (študentska soba 179±63 Bq/m3, dnevna soba 114±35 Bq/m3) ter povišane v kleti (1038±477 Bq/m3) in v starejši stavbi (1927±1461 Bq/m3). V nadaljevanju je bil poudarek raziskave na študentski sobi, kjer smo jeseni in pozimi, sočasno s koncentracijo 222Rn, kontinuirno merili še koncentracijo CO2 in spremljali pogostost in trajanje naravnega prezračevanja (odpiranje balkonskih vrat). Kljub pogostemu prezračevanju, so v obeh letnih časih zgodaj zjutraj koncentracije 222Rn večkrat presegle 250 Bq/m3, koncentracije CO2 pa 2000 ppm. Koncentracije 222Rn in CO2 smo nato še simulirali v programu CONTAM 3.4.0.1 z različnimi načrtovanimi stopnjami prezračevanja (DVR). Kriterij, ki smo ga pri tem upoštevali je bil, da koncentraciji 222Rn in CO2 ne presežeta mejne vrednosti (100 Bq/m3 za 222Rn in 1000 ppm za CO2). Jeseni smo ta pogoj dosegli pri 25,0 m3/h (0,5/h) za 222Rn in 69,9 m3/h (1,4/h) za CO2. Pozimi tega pogoja nismo mogli doseči za 222Rn niti z DVR 89,9 m3/h (1,8/h), za CO2 smo ga zagotovili pri DVR 69,9 m3/h (1,4/h). Ker tako visoke stopnje izmenjav zraka težko dosežemo z naravnim prezračevanjem, smo predlagali vgradnjo prezračevalnega sistema. Izračunali smo še letno efektivno dozo, ki jo zaradi 222Rn in produktov v zraku prejme oseba v študentski sobi (4 mSv), ki je višja od povprečne efektivne doze v svetovnem merilu (1,15 mSv/leto). Povišana efektivna doza še dodatno potrjuje smiselnost vgradnje prezračevalnega sistema.

Keywords

radon;ogljikov dioksid;stanovanjske stavbe;prezračevanje;efektivna doza;simulacije;magistrske naloge;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UNG FZO - Faculty of Environmental Sciences
Publisher: [T. Buh]
UDC: 504.5
COBISS: 115332611 Link will open in a new window
Views: 1105
Downloads: 44
Average score: 0 (0 votes)
Metadata: JSON JSON-RDF JSON-LD TURTLE N-TRIPLES XML RDFA MICRODATA DC-XML DC-RDF RDF

Other data

Secondary language: English
Secondary title: Optimization of natural ventilation in a single-family house with high radon concentration
Secondary abstract: Radon (222Rn) is a radioactive gas that increases the risk of lung cancer with prolonged exposure in humans. 222Rn enters buildings through a building envelope that is in contact with the ground; therefore, its concentration in the air of buildings depends on the concentration in the soil air, the quality of construction, meteorological factors and ventilation (natural or mechanical). For the research, we selected two adjacent residential buildings: (i) a newer inhabited, with good airtightness of the building envelope and (ii) an older, unoccupied, with poorer airtightness of the building envelope. In the period April–December 2021, 222Rn concentrations were measured in both buildings and, with the help of simulation, optimized ventilation in a newer building. Firstly, we performed three-day (i.e., short-term) continuous measurements of 222Rn concentration in selected rooms of both buildings. Based on the results, we selected rooms for further measurements in the newer (student room, living room and basement) and in the older building (bathroom), where a few-week (i.e., long-term) continuous measurements of 222Rn were performed in all seasons. We found that the average annual 222Rn concentrations in the newer building were below the reference level of 300 Bq/m3 (student room 179±63 Bq/m3, living room 114±35 Bq/m3) and increased in the basement (1038±477 Bq/m3) and the older building (1927±1461 Bq/m3). The focus of the research was on the student room, where simultaneously with the 222Rn concentration, CO2 concentration was continuously measured and monitored the frequency and duration of natural ventilation (opening the balcony door) in autumn and winter. Despite frequent ventilation, 222Rn concentrations exceeded 250 Bq/m3 in both seasons early in the morning several times, and CO2 concentrations exceeded 2000 ppm. The concentrations of 222Rn and CO2 were then simulated in the CONTAM 3.4.0.1 program with different Design Ventilation Rates (DVR). We considered a criterion: the concentrations of 222Rn and CO2 should not exceed the limit value (100 Bq/m3 for 222Rn and 1000 ppm for CO2). In autumn, this condition was reached at 25,0 m3/h (0,5/h) for 222Rn and 69,9 m3/h (1,4/h) for CO2. In winter, this condition was not met for 222Rn even with a DVR of 89,9 m3/h (1,8/h); for CO2, it was provided for a DVR of 69,9 m3/h (1,4/h). As such high levels of air exchange are difficult to ensure with natural ventilation, we proposed installing a ventilation system. We also calculated the annual effective dose received by a person in a student room (4 mSv) due to 222Rn and its products in the air, which is higher than the average effective dose worldwide (1,15 mSv/y). The increased effective dose further confirms the reasonableness of installing a ventilation system.
Secondary keywords: radon;carbon dioxide;residential house;ventilation;effective dose;simulation;
URN: URN:SI:UNG
Type (COBISS): Master's thesis/paper
Thesis comment: Univ. v Novi Gorici, Fak. za znanosti o okolju
Pages: XI, 66 str.
ID: 15824352