Towards upgrading strategies for nZEB-dwellings in Norway

Recent work suggests that upgrading in line with the Norwegian building regulations or by upgradingto the requirements of the national passive house norm, NS3700, can enable nZEB level to be achieved.The aim of this work is to explore the typical Norwegian housing typologies and some importantcharacteristics of the building envelope for these houses from different decades. The exploration involvedsurveying the typical technical qualities of Norwegian housing and how these have evolved – providingan important foundation to work addressing strategies and methods for upgrading dwellings to nZEBlevel in the next phases of the ongoing research project. The results of this work show that the buildingnorms and practices developed throughout the years have made dwellings more moisture resilient, withan increased drying-out potential through mechanical ventilation, control of the air change rate and theuse of more vapour-open wind barriers in the building envelope. Based on this, the work to follow willsuggest strategies for upgrading to nZEB level, solutions for upgrading building envelope componentsto high performance level and a methodology for risk reduction of moisture problems in the upgradeddwellings from the different decades.

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Indoor hygrothermal loads for the deterministic and stochastic design of the building envelope for dwellings in cold climates

Journal of Building Physics ◽

10.1177/1744259117718442 ◽

2017 ◽

Vol 41 (6) ◽

pp. 547-577 ◽

Cited By ~ 14

Author(s):

Simo Ilomets ◽

Targo Kalamees ◽

Juha Vinha

Keyword(s):

Field Measurements ◽

Heating System ◽

Building Envelope ◽

Cold Climates ◽

Outdoor Temperature ◽

Change Rate ◽

Levels Of Detail ◽

Air Change Rate ◽

Excess Value ◽

Occupancy Rates

In this study, several years of field measurements of indoor hygrothermal loads in 237 dwelling units are analysed. Moisture excess is calculated from hourly values of temperature, and relative humidity measured both indoors and outdoors. Air change rate and moisture production in bedrooms are calculated on the basis of carbon dioxide measurements. It is found that indoor temperature profiles differ depending on whether a building has central heating, a stove or combined heating system. The determined average moisture excess value, 2.8 g/m3 with a standard deviation of 1.6 g/m3 for cold periods, can be used in stochastic calculations. Critical values for moisture excess at the 90th percentile, ranging from 3–8 g/m3, depending upon occupancy rates, can be used in the deterministic analysis. Averages and weekly maxima of moisture excess in the study are reported at different percentiles. Considerable deviations from the EN ISO 13788 standard are discovered, concerning the breaking point depending on outdoor temperature and moisture excess during the summer. The average and critical moisture production in bedroom is presented and insufficient ventilation determined based on measurements. During the heating period, the air change rate is relatively stable while moisture production levels increase along with the dropping outdoor temperature. Two indoor temperatures and three humidity models with different levels of detail and influencing factors are proposed. Temperature and humidity loads derived using the proposed models can be used to determine the indoor hygrothermal boundary conditions for the building envelope of dwellings in cold climates.

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Analysis of Wind Speed and Wind Pressure on the Facades in Frequency Domain for the Modelling of Air Change Rate

E3S Web of Conferences ◽

10.1051/e3sconf/202017209005 ◽

2020 ◽

Vol 172 ◽

pp. 09005

Author(s):

Krystyna Pietrzyk

Keyword(s):

Wind Speed ◽

Frequency Domain ◽

Wind Direction ◽

High Frequency ◽

Pressure Coefficient ◽

Building Envelope ◽

Wind Pressure ◽

Change Rate ◽

Air Change Rate ◽

Air Exchange

Air exchange in buildings is driven by pressure difference across the building envelope caused by wind and difference in density between external and internal air. The evaluation of the influence of wind on the air change rate is usually limited to the analysis of the hourly mean wind speed. Wind is a random phenomenon characterized by the broad energy spectrum. The high frequency part can be responsible for the oscillation of the air through the openings resulting in the increased air exchange. Wind pressure coefficient on the leeward site mostly depends on the form characteristics of the object in relation to wind direction. The analysis of wind speed and wind pressure on the facades in frequency domain can deliver interesting data to air change rate model. Some of the results of continuous measurements carried out on a single-family house for 8 months are presented in frequency domain. The statistics of wind speed, wind direction and pressure differences across the 6 building components are calculated. The wind turbulence and the pressure fluctuations on the facades and the roof of the building are being investigated using energy spectra of their signals. Farther analysis of the experimental results is needed to be able to include high frequency wind in the infiltration model.

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Assessment of exposure risk from hidden fungal growth by measurements of air change rates in construction cavities and living areas

Journal of Building Physics ◽

10.1177/1744259117704386 ◽

2017 ◽

Vol 41 (3) ◽

pp. 209-224 ◽

Cited By ~ 1

Author(s):

Sofie M Knudsen ◽

Eva B Møller ◽

Lars Gunnarsen

Keyword(s):

Field Study ◽

Fungal Growth ◽

Building Envelope ◽

Exposure Risk ◽

Tracer Gas ◽

Change Rate ◽

Health Symptoms ◽

Air Change Rate ◽

Gaseous Pollution ◽

Growth Assessment

The transfer of particulate and gaseous pollution from hidden fungi growing on non-visible surfaces within the building envelope to occupied rooms is limited by the separating structure. Yet, growth, even in sealed construction cavities, is known to cause annoying smells and other more adverse health symptoms among the building occupants. This study analyses limitations of air change rate measurements in inaccessible construction cavities as well as analyses of the air exchange between living areas and accessible cavities such as crawl spaces and attics. It was necessary to invent a field study technique to use the tracer gas decay method in small and inaccessible cavities. This technique allowed further investigation on the exposure risk from hidden fungal growth. Assessment of the air transfer between crawl spaces and living areas indicate that the tightness of separating structure has an influence on the exposure risk.

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Radon emission rate and analysis of its influencing parameters

Nukleonika ◽

10.1515/nuka-2016-0056 ◽

2016 ◽

Vol 61 (3) ◽

pp. 337-342

Author(s):

Thomas Neugebauer ◽

Hans Hingmann ◽

Jonas Buermeyer ◽

Volker Grimm ◽

Joachim Breckow

Keyword(s):

Radon Concentration ◽

Emission Rate ◽

Digital Signal ◽

Building Envelope ◽

Entry Rate ◽

Change Rate ◽

Mean Values ◽

Air Change Rate ◽

Influencing Parameters ◽

Radon Emission

Abstract The geological and structural conditions define the radon situation inside a building. While the geological realities can be specified by the content of radium-226 and the ratio of radon-222 emitted from the ground the structural conditions are defined by the tightness of the building envelope. The radon concentration inside has an unsteady character, which is caused by meteorological conditions outside and the air change rate (ACH or ACR), which in turn is influenced by the residents’ behaviour such as venting and heating. For the assessment of the radon exposition, it is necessary to perform measurements for a long time. An approach to reduce this time by eliminating the inhabitants influence on the radon concentration is the radon emission rate, also known as radon entry rate. This variable is based on the measurement of the radon concentration and the parallel determination of the air change rate via a tracer gas method, the result expresses a released activity per time. Due to their noisy character, it is necessary to apply a smoothing algorithm to the input parameters. In addition to mean values, the use of window functions, known from digital signal processing, was analysed. For the verification of the whole calculation procedure, simulations and measurements under defined conditions were used. Furthermore, measurements in an uninhabited house showed proof of the capability of the assessment of the radon potential. First examinations of influencing parameters of the radon emission rate showed a possible dependence on the temperature difference inside and outside the building.

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Comparison of Downdraught and Up Draft Passive Air Conduction Systems (PACS) in a Winery Building

Buildings ◽

10.3390/buildings11060259 ◽

2021 ◽

Vol 11 (6) ◽

pp. 259

Author(s):

Ádám László Katona ◽

István Ervin Háber ◽

István Kistelegdi

Keyword(s):

Air Conditioning ◽

Natural Ventilation ◽

Dynamics Simulation ◽

Computational Fluid Dynamics Simulation ◽

General Applicability ◽

Change Rate ◽

Air Change Rate ◽

Simulation Based ◽

Ventilation Performance ◽

Air Conduction

A huge portion of energy consumption in buildings comes from heating, ventilation, and air conditioning. Numerous previous works assessed the potential of natural ventilation compared to mechanical ventilation and proved their justification on the field. Nevertheless, it is a major difficulty to collect enough information from the literature to make decisions between different natural ventilation solutions with a given situation and boundary conditions. The current study tests the passive air conduction system (PACS) variations in the design phase of a medium-sized new winery’s cellar and production hall in Villány, Hungary. A computational fluid dynamics simulation based comparative analysis enabled to determine the differences in updraft (UD) and downdraught (DD) PACS, whereby the latter was found to be more efficient. While the DD PACS performed an air change range of 1.02 h−1 to 5.98 h−1, the UD PACS delivered −0.25 h−1 to 12.82 h−1 air change rate. The ventilation performance of the DD version possessed lower amplitudes, but the distribution was more balanced under different wind incident angles, thus this version was chosen for construction. It could be concluded that the DD PACS provides a more general applicability for natural ventilation in moderate climates and in small to medium scale industry hall domains with one in- and one outlet.

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Determination of Optimal Air Change Rate for Cooling the Bedrooms of Residential Buildings in Guangzhou

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/719/2/022048 ◽

2021 ◽

Vol 719 (2) ◽

pp. 022048

Author(s):

Cuicui Qin ◽

Yufeng Zhang ◽

Lihua Zhao

Keyword(s):

Residential Buildings ◽

Change Rate ◽

Air Change Rate

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Evaluation of a High-Performance Solar Home in Loveland, Colorado

Journal of Solar Energy Engineering ◽

10.1115/1.2710248 ◽

2006 ◽

Vol 129 (2) ◽

pp. 226-234

Author(s):

Robert Hendron ◽

Mark Eastment ◽

Ed Hancock ◽

Greg Barker ◽

Paul Reeves

Keyword(s):

High Performance ◽

Energy Savings ◽

High Efficiency ◽

Building Envelope ◽

Operating Conditions ◽

Hot Water ◽

Space Heating ◽

Solar Water Heater ◽

Water Heater ◽

Solar Water

Building America (BA) partner McStain Neighborhoods built the Discovery House in Loveland, CO, with an extensive package of energy-efficient features, including a high-performance envelope, efficient mechanical systems, a solar water heater integrated with the space-heating system, a heat-recovery ventilator (HRV), and ENERGY STAR appliances. The National Renewable Energy Laboratory (NREL) and Building Science Consortium conducted short-term field-testing and building energy simulations to evaluate the performance of the house. These evaluations are utilized by BA to improve future prototype designs and to identify critical research needs. The Discovery House building envelope and ducts were very tight under normal operating conditions. The HRV provided fresh air at a rate of about 35L∕s(75cfm), consistent with the recommendations of ASHRAE Standard 62.2. The solar hot water system is expected to meet the bulk of the domestic hot water (DHW) load (>83%), but only about 12% of the space-heating load. DOE-2.2 simulations predict whole-house source energy savings of 54% compared to the BA Benchmark (Hendron, R., 2005 NREL Report No. 37529, NREL, Golden, CO). The largest contributors to energy savings beyond McStain’s standard practice are the solar water heater, HRV, improved air distribution, high-efficiency boiler, and compact fluorescent lighting package.

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