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In Finland, the indoor air conditions of 171 single-family buildings and 49 apartments in multi-family buildings have been studied in large research projects in collaboration with Tampere University of Technology and Helsinki University of Technology. This article deals with the results of moisture excess studied in these single-family buildings and apartments. Continuous field measurements up to 28 months enable to include two consecutive heating seasons in the analysis of the internal moisture excess. The higher 10% critical level during the cold period (Te ≤ 5°C) was between 3.4 and 4.9 g/m3 in Finnish heavyweight and lightweight single-family buildings and between 2.4 and 3.6 g/m3 in apartments of multi-family buildings. During the warm period (Te ≥ 15°C), the corresponding values were between 0.3 and 2.6 g/m3 for single-family buildings and 0.5 and 1.5 g/m3 for apartments. The number of occupants and the airtightness of different groups of external wall did not have influence on the average values of moisture excess. Slightly better ventilation air change rates were measured in apartments of multi-family buildings, where also the air change rates from supply–exhaust ventilation systems generally fulfilled the Finnish guideline value. The design values of moisture classes in EN ISO 13788:2012 were found difficult to apply for Finnish residential buildings. The upper limit value of humidity class 2 of EN ISO 13788:2012 is suitable for apartments in Finnish multi-family buildings, but too low for Finnish lightweight and heavyweight single-family buildings. Applying the design values of Finnish guidelines would be justified for the studied buildings almost at the full range of outdoor temperatures. [ABSTRACT FROM AUTHOR]

The paper presents a case study analysis of low-budget renovation of a typical concrete large-panel apartment building. Focus is on the measurements and analyses of energy consumption, indoor climate, CO2 concentration, air leakage rate, thermal transmittance of thermal bridges, and thermal transmittance of the building envelope before and after the renovation. Results indicate that the renovation project was generally successful, with delivered energy need decreasing by 40% and heating energy need decreasing by 50%. However, some key problems need to be solved to achieve full energy efficiency potential of the renovation works. Those critical problems are the performance (thermal comfort, heat recovery) of ventilation systems, thermal bridges of external wall/window jamb and economic viability. Currently, a major renovation is not economically viable, therefore financial assistance to the apartment owners’ associations is required to encourage them to undertake major renovations. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to evaluate possible ventilation solutions for nZEB multi apartment buildings in three European geoclusters. Geo-cluster concept illustrates trans-national areas where strong similarities are found in terms of climate, culture, construction typologies and other factors. Paper presents comparison of ventilation needs for the same case study building located in Denmark, Estonia, Latvia and Portugal. The economic and technical comparison of different ventilation systems are presented as well. Special focus is attended to develop introduction of modular solutions and integration of ventilation ducts into external insulation as this can serve as a complex solution including both external constructions and engineering networks. Presented modular solution includes prefabricated insulation panels with integrated ventilation ducts. This paper is prepared in scope of work done within EU HORIZON2020 MORE-CONNECT project. Research methodology is based on data analysis provided by project partners as well as practical calculation. Compilation of ventilation air volume requirements according to the local regulations for Latvia, Estonia, Portugal and Denmark has shown significant difference in design air change rate in project countries. The financial analysis reveals the price difference between various ventilation strategies and provides discussion topic regarding ventilation strategies in nZEB buildings. [ABSTRACT FROM AUTHOR]

Highlights: [•] Energy saving potential in historic wooden apartment buildings is up to 63%. [•] In historic wooden apartment buildings an economically viable energy saving level is 50%. [•] The largest energy saving potential lies in heat source and building service systems. [•] Of the building structures, insulation of the external wall has the highest potential. [•] New heating and ventilation systems must be installed to fulfill regulations limits. [Copyright &y& Elsevier]

In this study, the impact of ventilation requirements set in the conditions of a renovation grant was analysed with field measurements. Effects of renovation measures applied in two grant periods on the air change rate (ACR) and indoor air quality (IAQ) of apartments were examined. CO 2 levels and airflow rates were measured in 21 buildings during the first renovation grant period and in 15 buildings in the second grant period. During the first grant period, the average ACR studied apartments was as low as 0.17 h−1, and in the second grant period ACR had improved to 0.57 h−1, complying with requirements. Room-based ventilation requirements as well as heat recovery and preheating of intake air, mandatory airflow rate and sound pressure level measurement protocols, and third party inspection of design documentation assured adequate ventilation and IAQ in the second grant period. Centralized mechanical supply and exhaust ventilation with heat recovery resulted in best performance but an alternative system with exhaust heat pump and ventilation radiators may also be recommended. We concluded, that the installation of proper ventilation system is a key issue in renovation. The results of the study are a valuable input in designing technical conditions of the renovation grant. • Poorly designed renovation grants result in indoor air quality deterioration. • Air change in apartments strongly depends on the technical conditions of the grant. • Centralized balanced heat recovery ventilation showed the best performance. • Exhaust air heat pump with ventilation radiators is also recommended for renovation. • Renovation grant must require detailed requirements for ventilation solutions. [ABSTRACT FROM AUTHOR]

Abstract: Interest in finding out passive ways to keep the variation in the indoor climate within the comfort zone is gaining in popularity. One possible solution is the use of the moisture-buffering property of materials. In this study, the effects of the ventilation system and moisture-buffering properties of the building fabric on the stability of the indoor temperature and humidity are analysed by means of long-term field measurements. Indoor climate measurements were carried out in 170 detached houses (248 rooms). Temperature and relative humidity were measured continuously in bedrooms and living rooms at one-hour intervals over a one-year period. In general, it may be concluded that in this study, the ventilation had a greater effect on the indoor climate than the properties of the building fabric. The dampening effect of hygroscopic materials was remarkably less in the field measurements than it was in simulations in different studies. This indicates that completely non-hygroscopic and fully hygroscopic houses do not exist in reality. The hygroscopic mass of furniture, textiles, etc. is probably a factor that plays a significant role in indoor humidity, as do real air change rates, including window airing. Simulation tools need to be modified in order to be able also to handle furniture, textiles, and books, etc. [Copyright &y& Elsevier]

Abstract: Indoor moisture management, which means keeping the indoor relative humidity (RH) at correct levels, is very important for whole building performance in terms of indoor air quality (IAQ), energy performance and durability of the building. In this study, the effect of combining a relative-humidity-sensitive (RHS) ventilation system with indoor moisture buffering materials was investigated. Four comprehensive heat–air–moisture (HAM) simulation tools were used to analyse the performance of different moisture management strategies in terms of IAQ and of energy efficiency. Despite some differences in results, a good agreement was found and similar trends were detected from the results, using the four different simulation tools. The results from simulations demonstrate that RHS ventilation reduces the spread between the minimum and maximum values of the RH in the indoor air and generates energy savings. Energy savings are achieved while keeping the RH at target level, not allowing for possible risk of condensations. The disadvantage of this type of demand controlled-ventilation is that other pollutants (such as CO2) may exceed target values. This study also confirmed that the use of moisture-buffering materials is a very efficient way to reduce the amplitude of daily moisture variations. It was possible, by the combined effect of ventilation and wood as buffering material, to keep the indoor RH at a very stable level. [Copyright &y& Elsevier]

Abstract: This study analyses the airflow performance of a ventilated sub-flooring system that is only 3mm thick in laboratory and field conditions and with analytical modelling. Measurements and calculations showing good agreement were allowed to determine resultant equations for the sizing of the systems. It is shown that the design airflow keeps the floor under negative pressure, which prevents the penetration of odours and other contamination leakage to indoors. The design recommendations for ventilated sub-flooring systems are given. In the field study, the performance of the wall application of the system was shown. A quality assurance method was developed to ensure the required airflow in the ventilated sub-flooring system. Possible air leakages of the system can be found with a smoke detector and by real air-intake flow measurements to the floor made with an electronic soap film calibrator. [Copyright &y& Elsevier]

Abstract: A field measurement study of the air tightness and the air leakages of 32 detached houses was conducted during 2003–05 in Estonia. The buildings were classified according to the number of storeys, building technology, and the ventilation systems. Using the standardized BlowerDoor pressurization technique, the air leakage rate of each house was determined. To determine typical air leakage places and their distribution, an infrared image camera and a smoke detector were used. The mean air leakage rate at the pressure difference of 50Pa in the entire database was 4.2m3/(hm2). The mean air change rate at the pressure difference of 50Pa from the entire database was 4.91/h. It was found that the number of storeys and the quality of workmanship and supervision play a significant role in the condition of air tightness. The typical air leakage places in the studied houses were: the junction of the ceiling/floor with the external wall, the junction of the separating walls with the external wall, penetrations of the electrical and plumbing installations through the air barrier systems, penetrations of the chimney and ventilation ducts through the air barrier systems, leakage around and through electrical sockets and switches, and leakage around and through windows and doors. According to the questionnaire conducted, fluctuating room temperature, cold floors and draught from electric sockets were related to the houses with air leakage rate >3m3/(hm2) at 50Pa. [Copyright &y& Elsevier]

Field measurements of the indoor climate and ventilation performance have been carried out in 28 light-weight timber-frame detached houses occupied by single families during the years 2003-05 in Estonia. The temperature and relative humidity (RH) were continuously measured in bedrooms, living rooms and out- doors for each house at 1-h intervals over a 1-year period. The air change rates were calculated on the basis of the measured exhaust air flows. An extended period of high indoor temperatures during summer suggests that thermal comfort was not considered in the original design. During winter, large variations in temperature showed that problems existed with temperature control systems. During summer, only 13% and during winter, 45% of the rooms met the standard recommendations (with 5% excess) for temperatures in the lowest indoor climate category. This correspondence to standard recommendations was highest for the houses with balanced ventilation. The average ventilation air change rate at the level used by the occupants with a mechanical ventilation system was 0.41 ach (13.3 L·s-1 per person and 0.28 L·s-1·m-2). The performance of the ventilation had a significant influence on the average daily amplitude of the indoor temperature and humidity. According to a questionnaire, noise was associated with mechanical ventilation and stuffy air with natural ventilation. Fluctuating room temperature, cold floors and draught from electric sockets during winter were related to houses with air leakage of the building envelope >3m³.h-1·m-2) at 50 Pa. [ABSTRACT FROM AUTHOR]

Building simulation is increasingly being used in energy performance and indoor climate analysis and heating, ventilation and air conditioning systems design. Simulation requires hourly weather data. In this study Estonian climate was analysed to construct a test reference year for heating and cooling energy calculations and simulations according to a new standard, ISO15927-4. The selection was made on the basis of temperature, humidity, and global solar radiation and wind speed recordings at six weather stations over a period of 31 years, from 1970 to 2000. The constructed test reference year contains typical months from a number of different years. The average number of heating degree-days was calculated from data at six locations. The test reference year has many applications, including energy consumption and energy performance certificate calculations according to the directive about energy performance in buildings. [ABSTRACT FROM AUTHOR]

In this study, the indoor humidity loads in 101 lightweight timber-frame detached houses occupied by single families have been measured and analyzed. The temperature and relative humidity (RH) are measured at one-hour intervals over one-period in bedrooms, living rooms, and outdoors. Ventilation rates are measured with a passive tracer gas technique. Based on temperature and RH measurements, the difference between indoor and outdoor air absolute humidity is calculated. For hygrothermal design, the maximum moisture supply at the 10% critical level in the houses with low occupancy is +4 g/m³ during the cold period (Tout ≤ +5°C) Sand +1.5g/m³ during the warm period (Tout ≥ +15°C). Between these outdoor temperature values the moisture supply changed linearly. Different moisture supply levels and their dependence on outdoor temperature are given. An average moisture supply and moisture production values are calculated for the use of indoor climate simulations. A moisture supply design curve is given for the humidification case with a set point of 25% indoor RH. [ABSTRACT FROM AUTHOR]