Measured temperature and moisture conditions in the roof attic of a one-and-a-half story house

Nielsen, A. Levin; Morelli, Martin

doi:10.1016/j.egypro.2017.10.028

Cited by 6 publications

(8 citation statements)

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“…0.27 h −1 ) interior-attic air change rate is present (designs 16 and 32). However, when the attic is located in the south-west of Sweden, it remains moisture-risky whether ventilated or not (designs 23,20,18,19). Nevertheless, even in this area, ventilation helps the attic lower its moisture level to some extent when medium or high interior-attic airflow is present, even though this does not solve the problem completely (compare designs 20,18,19).…”

Section: Discussionmentioning

confidence: 99%

“…However, when the attic is located in the south-west of Sweden, it remains moisture-risky whether ventilated or not (designs 23,20,18,19). Nevertheless, even in this area, ventilation helps the attic lower its moisture level to some extent when medium or high interior-attic airflow is present, even though this does not solve the problem completely (compare designs 20,18,19). It is also interesting that some of these designs (18 and 19) were found to be risky according to the moisture-risk chart, even though their calculated mould indices are well below the mould-growth value.…”

Section: Discussionmentioning

confidence: 99%

“…This moisture can be transported into the attic by airflow (convection) and by diffusion (see Figure 5). Since airflow is the dominant mechanism of the two (considering ordinary construction and pressure differences), ceiling airtightness is the most recommended measure for achieving a moisture-safe cold attic [2,5,6,10,17,18,38,39]. The main flow pathways include leakages around attic staircases, electric conduits, ceiling fixtures, and other elements that penetrate the ceiling [3,5,39,40].…”

Section: Causes Of Problems and General Measuresmentioning

confidence: 99%

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Moisture-Safe Cold Attics in Humid Climates of Europe and North America

et al. 2020

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During the last few decades, unheated attic spaces (so-called “cold attics”) have been one of the most moisture-problematic spaces in the building practices of Europe and North America. Problems with such spaces are usually associated with condensation, frost formation, and mould growth on the lower surfaces of the roof deck. To solve these problems, a number of qualitative studies were performed. Although these studies revealed many important pieces of information, some of them are seemingly not in accordance with one another. Therefore, there has not yet been presented cold attic design which is suitable (especially moisture-safe) for the whole target region. The aim of this paper is to determine whether such a design can be determined or state the reasons why it is not possible. Based on a review of published studies, 38 cold attic designs were selected for detailed analysis. Their comparative parameters were established, quantified, and compared. The moisture-safeness of each design was evaluated using an original approach, and the designs were sorted into groups based on their similarities. Despite many uncertainties, it was found that the criteria for moisture-safe cold attic design in the target region can likely be stated.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Causes Of Problems and General Measuresmentioning

confidence: 99%

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Moisture-Safe Cold Attics in Humid Climates of Europe and North America

et al. 2020

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“…This represents a potential risk of condensation when the attics are ventilated using outdoor air. Harderup and Arfvidsson (2013), Kalagasidis (2004), Nielsen and Morelli (2017), Roppel and Lawton (2014) and Samuelson (1995) have similarly observed lower temperatures in the attic construction compared with the outdoor air during cold periods, with potential risk of condensation. Despite the increased temperature in the underlay, Figures 12 and 13 show slightly increased moisture concentration and mould growth risk.…”

Section: Effect Of Exterior Roof Insulationmentioning

confidence: 92%

Hygrothermal assessment of north-facing, cold attic spaces under the eaves with varying structural roof scenarios

Jensen

Bjarløv

Johnston

et al. 2019

Journal of Building Physics

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The objective of this study was to test whether compliance with the current Danish best practice recommendations concerning design of the cold attic space will prevent damaging moisture levels. The project was performed as a full-scale experimental setup in the cool temperate climate of Denmark. The setup comprised 18 north-facing attic spaces with varying ventilation principles and varying infiltration scenarios. The relative humidity and temperature were measured in attic spaces, indoor and outdoor, for almost 3 years. The hygrothermal performance of the attics was evaluated by post-processing and comparing the data with predicted mould growth risk and with visual observations of mould growth. The results showed that following the recommended passive ventilation strategies made the hygrothermal performance in attics with diffusion-open roofing underlay worse. In addition, increasing vapour diffusion tightness of the roofing underlay made the hygrothermal performance of the cold attic spaces under the eaves worse, except for attics with passive ventilation but without infiltration. The hygrothermal performance of the attics with diffusion-tight roofing underlay was poor when combining infiltration and the assessed ventilation strategy. The performance of the same attic without infiltration showed that some degree of ventilation was needed. External roof insulation did not significantly improve the hygrothermal performance of the attic.

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“…Furthermore, a lower temperature in the attic reduces the ventilation by stack effect, driven by temperature differences, and thus the ability to remove excess moisture is impeded. Some studies however, show that the amount of insulation does not have significant effect on the attic temperature [5,14] that appeared to be mostly dominated by outdoor temperature [15]. Most importantly, adequate ventilation of the cold attics with outdoor air seems important for the hygrothermal performance of the attic, and therefore, the application of postinsulation should not block any existing ventilation openings [16,17].…”

Section: Additional Ceiling Insulationmentioning

confidence: 99%

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

Hansen

2021

Buildings

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Naturally ventilated cold attics are traditional in many Danish single-family homes. The moisture balance of these attics is dependent on sufficient ventilation for removal of excess moisture. Moisture is generated in the dwelling below, and transported to attic spaces through convection and diffusion. Therefore, airtight ceilings are vital for reduction of excess moisture, which may yield mould growth in the attic. If mould spores migrate to the dwelling it can cause risk of health concerns for occupants. The presents study includes analysis of tracer gas and temperature/relative humidity measurements, in 30 dwellings/attics. The measurements yielded results of both air change rates in attics and dwellings, as well as air exchange between the two zones. Four of 30 houses, met the recommended air change rate of 0.5 h−1, and only in summer. The air change rate in the attics was found to be higher, and with larger variation compared to the dwelling. Visible mould growth was found in three attics, which all exhibited low air change rates. Air exchange between zones occurred in houses both with and without vapour barriers. The downward air exchange in summer, was however slightly larger in cases without vapour barriers. These results highlight the importance of airtight ceilings for both dwelling and attic performance.

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Measured temperature and moisture conditions in the roof attic of a one-and-a-half story house

Cited by 6 publications

References 0 publications

Moisture-Safe Cold Attics in Humid Climates of Europe and North America

Moisture-Safe Cold Attics in Humid Climates of Europe and North America

Hygrothermal assessment of north-facing, cold attic spaces under the eaves with varying structural roof scenarios

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

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