Dust in ventilation ducts : accumulation, measurement and removal

This thesis focuses on dust accumulation in, and removal from, recently installed supply air ducts and on the bristle behaviour of rotating duct cleaning brushes. The results of dust accumulation, measured using three different methods, were compared and the amount of dust in newly installed air ducts was evaluated. The vacuum test was found to be an efficient method of collecting dust samples on the duct surface. The vacuum test and the gravimetric tape method gave approximately the same results when the measured dust accumulation on the duct surfaces was 0.1-1.0 g/m2. The gravimetric and optical tape methods can be used to evaluate cleanliness of new ducts when the amount of dust accumulation is 0.1-1.0 g/m2. The effect of protection measures on dust accumulation was studied. The mean amount of accumulated dust after construction was 0.9 g/m2 in cleanliness category P1 ducts, which have special requirements for oil residues and protection measures against contamination during construction, and 2.3 g/m2 in cleanliness category P2 ducts, which have only minor protection requirements and are for normal use. The results show that dust accumulation in category P1 ducts was significantly lower (P < 0.008) than in category P2 ducts. The highest mean amount of dust accumulation was found in the middle of the ducts and the lowest amount near the air handling units. The efficiency of two dry air duct cleaning methods applied to new air ducts was compared. Mechanical brushing and compressed air cleaning methods were found to be efficient in removing dust from the newly installed air duct surfaces. Mechanical brushing was more efficient in metal ducts, while the compressed air cleaning method was more efficient in plastic ducts. The mean amount of residual dust on the duct surfaces was below 0.4 g/m2 after duct cleaning. However, neither of the cleaning methods studied was efficient enough to clean ducts that had a high level of residual oil (216-338 mg/m2) on the duct surfaces. A mathematical model to simulate the behaviour of a single bristle of a rotating duct cleaning brush was developed. The results of the simulation were compared with those obtained from a laboratory test. The simulated and experimental results were found to be in reasonable agreement. The dependence of the normal force and the contact angle as a function of various parameters was studied. The simulation and experimental results showed that the normal force and contact angle increase as a function of the rotation speed. Further, the thickness of the bristle was found to have a strong effect on the normal force. Air drag has only a slight effect on the deflection of the bristle. The model can be used as a first step in the systematic design of brushes. However, further theoretical and experimental research is needed to determine the dependency, for instance, between the brush tip normal force and its cleaning efficiency.reviewe

Kosteusvaurioiden vähentäminen rakennuksissa : Talotekniikkajärjestelmät rakennusten kosteusvaurioiden aiheuttajina

Lämpö ja kosteus aiheuttavat suurimman osan rakennusten kosteusvaurioista. Vauriot saattavat aiheuttaa sisäilmaongelmia, jos niitä ei korjata riittävän ajoissa. Suurin osa kosteusvaurioista voidaan välttää rakenteiden ja talotekniikkajärjestelmien oikealla suunnittelulla, huolellisella rakentamisella ja kunnossapidolla sekä rakennuksen ja sen järjestelmien oikealla käytöllä

Temperature distribution in regenerators

Heat recovery is a topical issue, as it affects building's energy effiency. This report presents an unusual approach to solving the regenerator temperature distribution: instead of using stepwise marching in time, we employ the finite element method using space-time elements and the Galerkin method. We also present it as a pure boundary value problem

The Barnacle Goose (Branta leucopsis) in the archipelago of southern Finland - population growth and nesting dispersal

We studied the population growth and expansion of Barnacle Goose (Branta leucopsis) in Helsinki archipelago, southern Finland. Barnacle Goose breeding was first recorded in Helsinki in 1989. During our study 1996-2013 the number of nesting geese increased from 24 to 740 pairs. We analyzed the role of protected islands in the population growth, and the factors behind differences in growth rates. Our study data consisted of 104 islands. Of these, 29 are protected from private recreational activity (nature reserve ormilitary areas) and were established prior to the start of our study. We predicted that protected areas would have a positive impact on Barnacle Goose population growth. In part of the study period (2002-2013) the population growth in our study area was much steeper in protected islands compared to islands with open access. However, breeding densities in those unprotected islands were higher than in protected islands in the early years of the study. We found that the most important factors affecting pair numbers in islands are island size and the time it has been inhabited, in addition to island distance from the islands southeast of Helsinki, where breeding expansion started. Island protection had no effect on the breeding geese numbers or current densities on the islands. Results indicate that early breeders like Barnacle Geese do not benefit from island protection probably because the recreational use of the islands is scant early in the spring.Peer reviewe

Crawling-induced floor dust resuspension affects the microbiota of the infant breathing zone

Background: Floor dust is commonly used for microbial determinations in epidemiological studies to estimate early-life indoor microbial exposures. Resuspension of floor dust and its impact on infant microbial exposure is, however, little explored. The aim of our study was to investigate how floor dust resuspension induced by an infant's crawling motion and an adult walking affects infant inhalation exposure to microbes. Results: We conducted controlled chamber experiments with a simplified mechanical crawling infant robot and an adult volunteer walking over carpeted flooring. We applied bacterial 16S rRNA gene sequencing and quantitative PCR to monitor the infant breathing zone microbial content and compared that to the adult breathing zone and the carpet dust as the source. During crawling, fungal and bacterial levels were, on average, 8- to 21-fold higher in the infant breathing zone compared to measurements from the adult breathing zone. During walking experiments, the increase in microbial levels in the infant breathing zone was far less pronounced. The correlation in rank orders of microbial levels in the carpet dust and the corresponding infant breathing zone sample varied between different microbial groups but was mostly moderate. The relative abundance of bacterial taxa was characteristically distinct in carpet dust and infant and adult breathing zones during the infant crawling experiments. Bacterial diversity in carpet dust and the infant breathing zone did not correlate significantly. Conclusions: The microbiota in the infant breathing zone differ in absolute quantitative and compositional terms from that of the adult breathing zone and of floor dust. Crawling induces resuspension of floor dust from carpeted flooring, creating a concentrated and localized cloud of microbial content around the infant. Thus, the microbial exposure of infants following dust resuspension is difficult to predict based on common house dust or bulk air measurements. Improved approaches for the assessment of infant microbial exposure, such as sampling at the infant breathing zone level, are needed.Peer reviewe

Arvorakennusten käytettävyys ja hyvät korjauskäytännöt : ARVO

Arvorakennusten korjauksia tehdään hyvin eritasoisina, erilaajuisina ja eri tavoin. ARVO-hankkeessa selvisi, että puutteet rakennuksen terveellisyyden arvioinnissa vaikuttavat korjausprosessin kaikkiin vaiheisiin. Hyvään arviointiin kuuluvat korjausprosessin lähtötietojen hankkiminen sekä laaja-alainen riskirakenteiden ja sisäilman epäpuhtauslähteiden huomioon ottaminen

Kuntoutuslaitokset muutoksessa – näkökulmia tilojen kehittämiseen

Kuntoutusala on murroksessa. Tässä raportissa kuvattu laaja, kansallinen KUNTO-projekti arvioi kuntoutuslaitosten toiminnan muutospaineita ja sitä, miten toimintojen muuttuminen tulisi ottaa huomioon tilasuunnittelussa.Hanke toteutettiin yhteistyössä Aalto-yliopiston ja siihen osallistuneiden kuntoutuslaitosten kanssa.1

Ilmanvaihtojärjestelmien puhtaus ja puhdistaminen sairaaloiden vuodeosastoilla

Ilmanvaihtojärjestelmien epäpuhtaudet voivat auheuttaa sisäilmaongelmia.Työterveyslaitos, Laadukas sisäympäristö -teema, Itä-Suomen yliopisto, Ympäristötieteen laitos, Tampereen ammattikorkeakoulu.1

Sisäilmaongelmien ennaltaehkäisy elinkaarimallia käytettäessä ja energiatehokkuutta tavoiteltaessa (SEEK)

Suomen kunnat ja kaupungit ovat käyttäneet erilaisia hankintamuotoja uusiin kouluihin ja peruskorjausten tekemiseen kouluissa. Elinkaarimalli on yksi perinteisten hankintamuotojen rinnalle kehitetty malli, jossa palveluntuottaja yhdellä sopimuksella vastaa ainakin hankkeen suunnittelusta, rakentamisesta ja ylläpidosta pitkän sopimuskauden (10−40 vuoden) ajan. Tässä tutkimuksessa kerättiin informaatiota suomalaisista elinkaarikouluista ja verrattiin tuloksia kaupungin omarahoitteisiin kouluihin, joiden huolto ja ylläpito oli tuotettu kaupungin omalla organisaatiolla. Tutkimus tehtiin vuosina 2014‒2016 kuudessa elinaarikoulussa ja kuudessa kaupungin omarahoitteisessa koulussa. Sisäympäristön laatua arvioitiin mittauksin ja käyttäjäkokemuksin. Lisäksi kouluissa arvioitiin rakennusteknisten tekijöiden vaikutusta sisäilman laatuun asiakirjatietojen ja kohteessa tehtyjen katselmusten avulla. Myös koulujen energiakulutustietoja arvioitiin ja verrattiin hankkeissa käytettyjä elinkaarisopimuksien sisältöjä