Hygrothermal performance of cold ventilated attics above different horizontal ceiling constructions – Field survey

Hansen, Thor; Moeller, Eva B.

doi:10.1016/j.buildenv.2019.106380

Cited by 8 publications

(14 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The pitched roof has a slope of 30 degrees and is oriented both South and North. Adequate ventilation of the attic was ensured by following the design rules in the Danish guidelines [2], in this case 2 x 50 cm 2 openings per metre at ridge, and effective opening area of 15 x 440 mm/m corresponding to 132 cm²/m at the two eaves. The air change rate per hour (ACH) was measured with passive tracer gas during several periods to 4 -10 h-1, which corresponds to values found in other studies, e.g.…”

Section: Methodsmentioning

confidence: 99%

“…Traditionally the airtightness of the ceiling has been ensured by a plastered ceiling without cracks. Vapour barrier was introduced in this type of constructions in the 1960's and was expected to ensure air and vapour tightness of the construction [2]. However, limited focus was paid on the sealing of the connections and details, and in practice the vapour barriers were not as tight as they nominally should.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Towards moisture safe ventilated cold attics – Monitored conditions in a full-scale test building

2020

Self Cite

View full text Add to dashboard Cite

Existing building stock in Europe accounts for approx. 40% of the total energy consumption. Upgrading the thermal insulation of the existing buildings is an important measure to reduce heat losses through the building envelope. In some cases, increasing the thermal resistance of the construction may compromise the hygrothermal performance of the retrofitted construction. In particular, if vapour barrier is necessary for the good performance and it is practically difficult, if not even impossible, to install a well-sealed air- and vapour tight layer. To investigate the robustness of the hygrothermal performance of ventilated cold attics – with or without a vapour barrier – a monitoring campaign in a full-scale test building was set up. Also role of number of other parameters like moisture buffering capacity of the insulation material and thermal resistance was investigated. This paper presents part of this measuring campaign, which includes conditions both in the attic space and inside the insulation layer. The monitored data covers a period with two winters. The results show that it in temperate climate is practically indifferent for the hygrothermal performance of the monitored, well-ventilated attics with air-tight ceilings whether there is a vapour barrier or not and if the insulation material has moisture buffering capacity or not.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Towards moisture safe ventilated cold attics – Monitored conditions in a full-scale test building

2020

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although climate zones can shift in the future [37], potential moisture-safe attic designs should always be valid for a particular climate-cultural region. Although past studies revealed many important pieces of information, some of them are not in agreement with one another as noted by some of the recent studies [15,16]. An example can be illustrated using one of the most discussed parameters of attic design-the ventilation.…”

Section: Target Regionmentioning

confidence: 97%

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

et al. 2020

View full text Add to dashboard Cite

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.

show abstract

“…According to [18], cellulose-based insulation can absorb 10-40 times more moisture than mineral wool, due to the hygroscopic properties; hence having a moisture-buffering effect. However, full-scale studies as well as field studies have not been able to establish this effect [16,19]. Some measurements do however indicate marginally lower moisture conditions in cold attics with hygroscopic insulation materials [20].…”

Section: Additional Ceiling Insulationmentioning

confidence: 99%

“…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]. The type of insulation material applied on the ceiling may have an effect on the overall hygrothermal conditions in the attic.…”

Section: Additional Ceiling Insulationmentioning

confidence: 99%

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

Hansen

2021

Buildings

View full text Add to dashboard Cite

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.

show abstract

Hygrothermal performance of cold ventilated attics above different horizontal ceiling constructions – Field survey

Cited by 8 publications

References 14 publications

Towards moisture safe ventilated cold attics – Monitored conditions in a full-scale test building

Towards moisture safe ventilated cold attics – Monitored conditions in a full-scale test building

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

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

Contact Info

Product

Resources

About