Spatiotemporal humidity variation in student housing

Modern, urban apartments are space-efficient, have bathrooms with no windows, and require energy-efficient ventilation with heat recovery. The requirements for exhaust ventilation rates for the kitchen and bathrooms are independent of dwelling size. In some countries, it is required that the extract air can be increased on demand. There is a need for more knowledge on the effects of these requirements on the resulting moisture level in apartments, and whether these recommendations should be modified. Measurements were done in eight student apartments. Temperature and humidity were measured with 1-minute time resolution at 5 locations in each of the apartments. Median moisture excess was 0.9-1.4 g/m³, indicating a small risk of interstitial condensation. 90th percentiles of relative humidity were 30-35 %, indicating an elevated risk of eye and airway symptoms due to low humidity. The moisture excess was lower in apartments with heat-recovery ventilation than mechanical extract ventilation. The median moisture excess was higher in the living rooms than in bathrooms, indicating that moisture from showering and personal hygiene had little impact on the overall indoor moisture conditions in the dwellings. The average number of showers per day per apartment varied between 0.6 and 3.1. High peak moisture excess values up to 20 g/m³ were recorded in bathrooms, but for brief periods only. Consistently higher moisture peaks in extract vents than in bathroom air demonstrated that ventilation extract above the shower is effective in removing moist air from showering. Calculated moisture load in the extract air from a single shower was estimated to be 0.86 kg. Outdoor temperatures were negatively correlated with moisture excess, as predicted by EN -ISO 13788.publishedVersio

A Numerical Study on the Impact of Wind Gust Frequency on Air Exchanges in Buildings with Variable External and Internal Leakages

Wind-driven air infiltration has been recognized among the major reasons for energy loss in buildings, and the impact to energy efficiency under steady conditions has been reported and issued as part of many building codes. The nearly zero-energy building demand makes uncontrolled leakage paths even more undesired and creates the need for further investigation of their behavior under unsteady wind conditions. The present numerical study examines the role of wind gustiness on instantaneous infiltration rates of a low-rise building. For this purpose, two levels of gust frequency Ω have been simulated, expressed as a sinusoidal factor in the wind profile formula. In parallel, a ratio α is employed to represent seven different cases of external leakages distribution, while five scenarios of compartmentalization and internal leakages shows the impact of the latter on the dynamics of building air exchange rates. The results indicate that higher wind gustiness results in higher ACH, marking out gusts as a potential critical factor under unsteady climate conditions. The infiltration rates shown in relation to the leakage distribution ratio α provide arguments for the importance of the detailed detection of external leakages while the comparison of the different internal-volume-scenario highlights the key-role of internal leakages control towards a drastic reduction of infiltration rates

Full-Scale Measurements of Wind-Pressure Coefficients in Twin Medium-Rise Buildings

Wind pressure coefficients (Cp) are important values for building engineering applications, such as calculation of wind loads or wind-induced air infiltration and especially for tall buildings that are more susceptible to wind forces. Wind pressure coefficients are influenced by a plethora of parameters, such as building geometry, position on the façade, exposure or sheltering degree, and wind direction. On-site measurements have been performed on a twin medium-rise building complex. Differential pressure measurements have been employed in order to determine the wind pressure coefficients at various positions along the windward façades of the twin buildings. The measurements show that one building provides substantial wind shelter to its twin and the microclimatic effect is captured by the measured wind pressure coefficients. They also showed that the wind pressure coefficients vary significantly spatially along the windward façades of the medium-rise buildings. Furthermore, the pressure measurements showed that the wind pressure coefficients fluctuate significantly during the measuring period. The use of the fluctuating Cp values by means of probability distribution function (pdf) for the calculation of air infiltration has been evaluated. The results indicate that the air flows deriving using fluctuating Cp values are more accurate than the ones calculated by the conventional method of using mean Cp values

Moisture buffering, energy potential, and volatile organic compound emissions of wood exposed to indoor environments

The use of wood in built environments has been increasing during the last decades, and more focus has been set on the influence of wood surfaces on indoor environments on the objective and subjective measures of human well-being. In addition, the moisture buffer capacity of hygroscopic materials, such as wood, has been under investigation in order to quantify the impact of wooden surfaces on energy savings in buildings. The current study presents the results of wood surfaces and indoor air temperatures as well as indoor air relative humidity measured in two solid timber test houses. The findings reveal a substantial effect on wood surface temperature under fluctuating indoor relative humidity due to the latent heat of sorption of water vapors. The results were compared with hygrothermal numerical simulations, showing good agreement and the validated numerical model was used in order to quantify the energy performance in a bathroom when the latent heat of sorption is exploited. The combination of wood with a well-controlled HVAC system in rooms with moisture production shows significant potential for indirect energy savings by adjusting the indoor temperature and exploiting the increase of surface temperature in the hygroscopic structure. Furthermore, the emissions of volatile organic compounds from pine wood were studied in laboratory facilities, with focus on the variations of emissions due to diurnal fluctuations in air humidity. Human participants were exposed in a large test chamber to a concealed source of volatile organic compound emissions in the form of fresh pine wood, while the actual exposure reached air levels of monoterpenes up to 18 mg/m3 during the intervention situation. Perceptions of air quality and mucosal irritation effects were reported in a standard questionnaire during this double-blind test with no irritation effects reported

Moisture buffering, energy potential, and volatile organic compound emissions of wood exposed to indoor environments

The use of wood in built environments has been increasing during the last decades, and more focus has been set on the influence of wood surfaces on indoor environments on the objective and subjective measures of human well-being. In addition, the moisture buffer capacity of hygroscopic materials, such as wood, has been under investigation in order to quantify the impact of wooden surfaces on energy savings in buildings. The current study presents the results of wood surfaces and indoor air temperatures as well as indoor air relative humidity measured in two solid timber test houses. The findings reveal a substantial effect on wood surface temperature under fluctuating indoor relative humidity due to the latent heat of sorption of water vapors. The results were compared with hygrothermal numerical simulations, showing good agreement and the validated numerical model was used in order to quantify the energy performance in a bathroom when the latent heat of sorption is exploited. The combination of wood with a well-controlled HVAC system in rooms with moisture production shows significant potential for indirect energy savings by adjusting the indoor temperature and exploiting the increase of surface temperature in the hygroscopic structure. Furthermore, the emissions of volatile organic compounds from pine wood were studied in laboratory facilities, with focus on the variations of emissions due to diurnal fluctuations in air humidity. Human participants were exposed in a large test chamber to a concealed source of volatile organic compound emissions in the form of fresh pine wood, while the actual exposure reached air levels of monoterpenes up to 18 mg/m3 during the intervention situation. Perceptions of air quality and mucosal irritation effects were reported in a standard questionnaire during this double-blind test with no irritation effects reported

Kuldebroer – Beregning, kuldebroverdier og innvirkning på energibruk

I denne rapporten blir følgende presentert: • Definisjon av kuldebro • Mulige konsekvenser av kuldebroer • Metoder for å bestemme kuldebroverdien, inkl. ved numerisk beregning • Kuldebroverdier for forskjellige konstruksjoner • Et forslag til dynamisk KuldebroAtlas Prosjektrapporten viser kuldebroverdier for forskjellige konstruksjoner som for eksempel for vindusinnsetting,overgang mellom vegg/tak, vegg/golv, for hjørner og for møne. Kuldebroverdier for etasjeskillere er også vist, og da for forskjellige typer etasjeskillere som betong, lettklinker og hulldekker.Rapporten viser at kuldebroverdien kan variere mye for hver enkelt detalj, og er spesielt avhengig av tykkelsen på kuldebrobryter. Videre vil kuldebroverdien for hvordan et vindu monteres i en vegg variere forholdsvis mye (fra 0,01 til 0,05 W/mK). For konstruksjoner på grunnen er det vanskelig å komme under en kuldebroverdi på 0,04 W/mK, siden det der vil være en geometrisk kuldebro i tillegg til materialbidraget. Rapporten er finansiert av Husbanken, Boligprodusentenes forening, AF Gruppen, Skanska, Veidekke, Glava og Rockwool

Kuldebroer – Beregning, kuldebroverdier og innvirkning på energibruk

I denne rapporten blir følgende presentert: • Definisjon av kuldebro • Mulige konsekvenser av kuldebroer • Metoder for å bestemme kuldebroverdien, inkl. ved numerisk beregning • Kuldebroverdier for forskjellige konstruksjoner • Et forslag til dynamisk KuldebroAtlas Prosjektrapporten viser kuldebroverdier for forskjellige konstruksjoner som for eksempel for vindusinnsetting,overgang mellom vegg/tak, vegg/golv, for hjørner og for møne. Kuldebroverdier for etasjeskillere er også vist, og da for forskjellige typer etasjeskillere som betong, lettklinker og hulldekker.Rapporten viser at kuldebroverdien kan variere mye for hver enkelt detalj, og er spesielt avhengig av tykkelsen på kuldebrobryter. Videre vil kuldebroverdien for hvordan et vindu monteres i en vegg variere forholdsvis mye (fra 0,01 til 0,05 W/mK). For konstruksjoner på grunnen er det vanskelig å komme under en kuldebroverdi på 0,04 W/mK, siden det der vil være en geometrisk kuldebro i tillegg til materialbidraget. Rapporten er finansiert av Husbanken, Boligprodusentenes forening, AF Gruppen, Skanska, Veidekke, Glava og Rockwool

Moisture buffering, energy potential, and volatile organic compound emissions of wood exposed to indoor environments

This is the author’s version of the article published in Science and Technology for the Built Environment.The article has been peer-reviewed, but does not include the publisher’s layout, page numbers and proof-corrections.Citation for the published paper: Nore, K., Nyrud, A. Q., Kraniotis, D., Skulberg, K. R., Englund, F. & Aurlien, T. (2017). Moisture buffering, energy potential, and volatile organic compound emissions of wood exposed to indoor environments. Science and Technology for the Built Environment, 23(3), 512-521. doi: http://dx.doi.org/10.1080/23744731.2017.1288503The use of wood in built environments has been increasing during the last decades, and more focus has been set on the influence of wood surfaces on indoor environments on the objective and subjective measures of human well-being. In addition, the moisture buffer capacity of hygroscopic materials, such as wood, has been under investigation in order to quantify the impact of wooden surfaces on energy savings in buildings. The current study presents the results of wood surfaces and indoor air temperatures as well as indoor air relative humidity measured in two solid timber test houses. The findings reveal a substantial effect on wood surface temperature under fluctuating indoor relative humidity due to the latent heat of sorption of water vapors. The results were compared with hygrothermal numerical simulations, showing good agreement and the validated numerical model was used in order to quantify the energy performance in a bathroom when the latent heat of sorption is exploited. The combination of wood with a well-controlled HVAC system in rooms with moisture production shows significant potential for indirect energy savings by adjusting the indoor temperature and exploiting the increase of surface temperature in the hygroscopic structure. Furthermore, the emissions of volatile organic compounds from pine wood were studied in laboratory facilities, with focus on the variations of emissions due to diurnal fluctuations in air humidity. Human participants were exposed in a large test chamber to a concealed source of volatile organic compound emissions in the form of fresh pine wood, while the actual exposure reached air levels of monoterpenes up to 18 mg/m3 during the intervention situation. Perceptions of air quality and mucosal irritation effects were reported in a standard questionnaire during this double-blind test with no irritation effects reported.acceptedVersio