Danish Dwellings with Cold Attics—Ventilation Rates and Air Exchange between Attic and Dwelling

Hansen, Tessa Kvist

doi:10.3390/buildings11020064

Cited by 4 publications

(3 citation statements)

References 18 publications

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“…where the slope of the roof is different, the building shape and, thereby the attic space, more complex, the building is exposed to more wind, or the ventilation openings distributed differently. Hansen [9] shows a high variation in the ventilation rate in attics above single-family houses in Denmark, although -theoretically -they are all built according to the same guidelines used in this study. Therefore, one should be careful to use this single study with a simple geometry and high attention to airtightness of the ceiling to conclude that the current guideline of ventilation openings could be reduced.…”

Section: Hygrothermal Conditionsmentioning

confidence: 96%

Openings in ventilated Attics

Møller,

Morelli,

Hansen

2023

J. Phys.: Conf. Ser.

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How big should ventilation openings be in ventilated attics? In Denmark, guidelines describe what is sufficient to remove excess moisture penetrating through the ceiling. These guidelines are based on many years of experience. An important parameter is the tightness of the ceiling. With current regulations for the airtightness of buildings, convection through the ceiling is reduced compared to older buildings. Therefore, it is relevant to review these old rules of thumb and maybe revise them. In this two-year study, tests with different sizes of ventilation openings were conducted in a test house with 18 separate ventilated attics and airtight ceilings. One third of the attics were ventilated according to the guidelines, one third’s ventilation was reduced by one third and the last third had 50 % ventilation of the recommendations. Hourly measurements of temperature and relative humidity in the attics were conducted. Rafters in the attics were tested for mould growth. Six different types of insulation systems were used in the attics (with and without a vapour barrier, different insulation materials, and insulation thickness), therefore, the study also includes these differences. Earlier investigations, with full ventilation in all attics, showed no significant hygrothermal differences between them; consequently, it was assumed that the amount of ventilation would be decisive for the hygrothermal performance. This study follows up on this assumption. Results show little differences between the attics, mainly that having a vapour barrier becomes more important with reduced ventilation, and the insulation thickness and thereby U-value is of less importance. Reducing the requirements for ventilation of attics could be relevant, provided that the ceiling is airtight.

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Section: Hygrothermal Conditionsmentioning

confidence: 96%

Openings in ventilated Attics

Møller,

Morelli,

Hansen

2023

J. Phys.: Conf. Ser.

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“…Among the few published findings are these: Walker and Forest measured attic ventilation rates; 27 transport throughout a residence; 28 and Hansen characterized ventilation rates from the attic to the living space. 29 A recent indoor air review did not indicate any further examination of the attic as a source of VOCs in either indoor or outdoor air. 30 Some work has characterized attic dust composition, 31,32 but that is also limited.…”

Section: ■ Introductionmentioning

confidence: 99%

“…An understudied but ubiquitous residential indoor space is the attic. Among the few published findings are these: Walker and Forest measured attic ventilation rates; Liu et al explored total attic VOC concentrations and interzonal transport throughout a residence; and Hansen characterized ventilation rates from the attic to the living space . A recent indoor air review did not indicate any further examination of the attic as a source of VOCs in either indoor or outdoor air .…”

Section: Introductionmentioning

confidence: 99%

Volatile Organic Compound Composition and Emissions in a Residential Attic

Molinier,

Arata,

Lunderberg

et al. 2024

ACS EST Air

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Volatile organic compounds (VOCs) are important constituents of indoor and urban air pollution. Emissions into building attics have rarely been studied, resulting in a lack of information about this potentially important air pollution source. VOC transport from residential attics to outdoor air is generally missing from emission inventories. In this study, attic VOC concentrations and emissions were assessed in a normally-occupied single-family residence in Oakland, California over 10 weeks during autumn 2021. A proton-transfer-reaction time-offlight mass spectrometer was utilized to sequentially measure VOC concentrations in the attic, the living space, and outdoors at a rate of twice per hour. Over 200 VOCs were detected at concentrations averaging above five parts per trillion, including many known to be emitted from building materials and wood decomposition. Inert tracer gases were continuously released at known rates into the attic, living zone, and basement to characterize air change rates and interzonal flows. Combining the measurements in a material-balance model, we determine time-resolved and speciated VOC emission factors into the attic and to outdoors from the attic. We find that furfural is a key indicator species and that large diurnal temperature changes in the attic significantly influence VOC emissions from the attic to outdoors.

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