Building leakage,infiltration, and energy performance analyses for Finnish detached houses

This study focuses on the relation between the airtightness of a building envelope, infiltration, and energy use of a typical modern Finnish detached house in the cold climate of Finland. The study is conducted with an empirically tested dynamic IDA-ICE simulation model of a detached house. The effect of several factors, such as Finnish climate and wind conditions, balance of ventilation system and leakage distribution, on infiltration was studied and a simple adapted model for the rough estimation of annual infiltration in Finnish detached houses was determined from the numerical simulation results. The energy impact of infiltration is also studied, taking into account the infiltration heat recovery effect. According to the results, infiltration causes about 15–30% of the energy use of space heating including ventilation in the typical Finnish detached house. The average infiltration rate and heat energy use increase almost linearly with the building leakage rate n₅₀. Finland can be roughly divided into two zones based on the average infiltration rate of detached houses, for which stack-induced infiltration is typically dominant, regardless of the climate zone. The infiltration heat recovery effect is minor in the studied detached house.     

Volatile organic compound concentrations and emission rates in new manufactured and site-built houses

Concentrations of 54 volatile organic compounds (VOCs) and ventilation rates were measured in four new manufactured houses over 2-9.5 months following installation and in seven new site-built houses 1-2 months after completion. The houses were in four projects located in hot-humid and mixed-humid climates. They were finished and operational, but unoccupied. Ventilation rates ranged from 0.14-0.78 h-1. Several of the site-built houses had ventilation rates below the ASHRAE recommended value. In both manufactured and site-built houses, the predominant airborne compounds were alpha-pinene, formaldehyde, hexanal, and acetic acid. Formaldehyde concentrations were below or near 50 ppb with a geometric mean value for all houses of 40 ppb. Similarities in the types of VOCs and in VOC concentrations indicated that indoor air quality in the houses was impacted by the same or similar sources. Major identified sources included plywood flooring, latex paint and sheet vinyl flooring. One site-built house was operated at ventilation rates of 0.14 and 0.32 h-1. VOC emission rates calculated at the two conditions agreed within +/- 10% for the most volatile compounds. Generally, the ratios of emission rates at the low and high ventilation rates decreased with decreasing compound volatility. Changes in VOC emission rates in the manufactured houses over 2-9.5 months after installation varied by compound. Only several compounds showed a consistent decrease in emission rate over this period.     

The development of low volatile organic compound emission house—a case study

An aim in developing low volatile organic compound (VOCs) emission house is to reduce the level of VOCs in domestic housing. In this study, a case study for the reduction of exposure to VOCs from a newly constructed residential house was presented. Before application, the construction materials used in the house were tested in an environmental chamber and low VOC emission materials were then selected. Design of the house abided by the following principals: maximizing the ventilation rate and avoiding the use of high VOC emission materials in the house. By improved building design and proper construction materials selection, risk of personal exposure to VOCs in the house was significantly reduced. The total VOCs (TVOCs) concentrations measured in the house ranged from non-detectable to 43 μg/m³. These values were much lower than the published values (0.48–31.7 mg/m³) for new houses in Scandinavian countries and in the USA. The low TVOCs concentrations obtained in this study probably resulted from the high ventilation rates and the use of low VOCs emission materials. This study also combined the results with the three traditional ways in improvement of IAQ. The results obtained in this study confirmed that the most effective strategy for controlling IAQ was pollution prevention and the next most important was the design of ventilation rates to handle uncontrollable sources. The effectiveness of aging as a means of indoor pollution control was also reviewed.     

Microbial contamination of indoor air due to leakages from crawl space: a field study

Mechanical exhaust ventilation system is typical in apartment buildings in Finland. In most buildings the base floor between the first floor apartments and crawl space is not air tight. As the apartments have lower pressure than the crawl space due to ventilation, contaminated air may flow from the crawl space to the apartments. The object of this study was to find out whether a potential air flow from crawl space has an influence on the indoor air quality. The results show that in most cases the concentration of fungal spores was clearly higher in the crawl space than inside the building. The size distribution of fungal spores depended on the fungal species. Correlation between the fungal spores in the crawl space and indoors varied with microbial species. Some species have sources inside the building, which confounds the possible relation between crawl pace and indoor concentrations. Some species, such as Acremonium, do not normally have a source indoors, but its concentration in the crawl space was elevated; our measurements showed also elevated concentrations of Acremonium in the air of the apartments. This consistent finding shows a clear linkage between fungal spores in the indoor air and crawl space. We conclude that a building with a crawl space and pressure difference over the base floor could be a potential risk for indoor air quality in the first floor apartments.     

Air pollution sources in offices and assembly halls,quantified by the olf unit

Pollution sources were quantified by the new olf unit in 20 randomly selected offices and assembly halls in Copenhagen. The spaces were visited three times by 54 judges, who assessed the acceptability of the air: (1) while unoccupied and unventilated to quantify pollution sources in the space; (2) while unoccupied and ventilated to quantify pollution sources in the ventilation system; and (3) while occupied and ventilated to determine pollution caused by occupants and smoking. Ventilation rates, carbon dioxide, carbon monoxide, particulates, and total volatile organic compounds were measured, but did not explain the large variations in perceived air quality. For each occupant in the 15 offices there were on average 6–7 olfs from other pollution sources; 1–2 olfs were situated in the materials in the space, 3 olfs in the ventilation system, and 2 olfs were caused by tobacco smoking. The ventilation rate was 25 l/s per occupant, but due to the extensive other pollution sources only 4 l/s per olf. This explains why an average of more than 30% of the subjects found the air quality in the offices unacceptable. The obvious way to improve indoor air quality is to remove pollution sources in the spaces and in the ventilation systems. This will at the same time improve air quality, decrease required ventilation and energy consumption, and diminish the risk of draughts.     

Airtightness and ventilation strategy in Japanese residences

In this paper, the relationship between airtightness and indoor air quality is shown, based on measurements made of thirteen detached wooden houses. Secondly, a chart for predicting air infiltration from airtightness rank is given, and the relationship between airtightness and air infiltration is discussed. Finally, optimum combinations of heating and ventilating systems and types of cooking appliances are suggested according to the airtightness rank of a house.     

The modifying effect of the building envelope on population exposure to PM2.5 from outdoor sources

A number of studies have estimated population exposure to PM_2.5 by examining modeled or measured outdoor PM_2.5 levels. However, few have taken into account the mediating effects of building characteristics on the ingress of PM_2.5 from outdoor sources and its impact on population exposure in the indoor domestic environment. This study describes how building simulation can be used to determine the indoor concentration of outdoor‐sourced pollution for different housing typologies and how the results can be mapped using building stock models and Geographical Information Systems software to demonstrate the modifying effect of dwellings on occupant exposure to PM_2.5 across London. Building archetypes broadly representative of those in the Greater London Authority were simulated for pollution infiltration using EnergyPlus. In addition, the influence of occupant behavior on indoor levels of PM_2.5 from outdoor sources was examined using a temperature‐dependent window‐opening scenario. Results demonstrate a range of I/O ratios of PM_2.5, with detached and semi‐detached dwellings most vulnerable to high levels of infiltration. When the results are mapped, central London shows lower I/O ratios of PM_2.5 compared with outer London, an apparent inversion of exposure most likely caused by the prevalence of flats rather than detached or semi‐detached properties.     

Formaldehyde as a basis for residential ventilation rates

Traditionally, houses in the US have been ventilated by passive infiltration in combination with active window opening. However in recent years, the construction quality of residential building envelopes has been improved to reduce infiltration, and the use of windows for ventilation also may have decreased due to a number of factors. Thus, there has been increased interest in engineered ventilation systems for residences. The amount of ventilation provided by an engineered system should be set to protect occupants from unhealthy or objectionable exposures to indoor pollutants, while minimizing energy costs for conditioning incoming air. Determining the correct ventilation rate is a complex task, as there are numerous pollutants of potential concern, each having poorly characterized emission rates, and poorly defined acceptable levels of exposure. One ubiquitous pollutant in residences is formaldehyde. The sources of formaldehyde in new houses are reasonably understood, and there is a large body of literature on human health effects. This report examines the use of formaldehyde as a means of determining ventilation rates and uses existing data on emission rates of formaldehyde in new houses to derive recommended levels. Based on current, widely accepted concentration guidelines for formaldehyde, the minimum and guideline ventilation rates for most new houses are 0.28 and 0.5 air changes per hour, respectively.     

Characterizations,relationship, and potential sources of outdoor and indoor particulate matter bound polycyclic aromatic hydrocarbons (PAHs) in a community of Tianjin,Northern China

Polycyclic aromatic hydrocarbons (PAHs) are among the most toxic air pollutants in China. However, because there are unsubstantial data on indoor and outdoor particulate PAHs, efforts in assessing inhalation exposure and cancer risk to PAHs are limited in China. This study measured 12 individual PAHs in indoor and outdoor environments at 36 homes during the non‐heating period and heating period in 2009. Indoor PAH concentrations were comparable with outdoor environments in the non‐heating period, but were lower in the heating period. The average indoor/outdoor ratios in both sampling periods were lower than 1, while the ratios in the non‐heating period were higher than those in the heating period. Correlation analysis and coefficient of divergence also verified the difference between indoor and outdoor PAHs, which could be caused by high ventilation in the non‐heating period. To support this conclusion, linear and robust regressions were used to estimate the infiltration factor to compare outdoor PAHs to indoor PAHs. The calculated infiltration factors obtained by the two models were similar in the non‐heating period but varied greatly in the heating period, which may have been caused by the influence of ventilation. Potential sources were distinguished using a diagnostic ratio and a mixture of coal combustion and traffic emission, which are major sources of PAHs.     

重庆初装修房与精装修房室内环境污染的对比分析及控制措施

重庆初装修房室内环境污染物浓度较低,建议检测时可减小抽检数量;精装修房室内环境污染物浓度高于初装修房,污染状况令人担忧,应以目前国内技术和经济条件为基础,从建筑材料控制、设计、施工、检测等几个方面对室内环境污染物浓度进行控制。     

Indoor air pollution by alkylphenols in Tokyo

The purposes of this study were to develop an analytical method for airborne alkylphenols (APs) using the gas chromatography/mass spectrometry (GC/MS)-SIM method and to investigate airborne C4-C9 APs pollution in houses, offices, and outdoor points in Tokyo. In addition, to identify APs emission sources in a newly built house, migration tests of APs from interior surfaces to solid extraction disks were performed. Air samples were collected from houses, offices, and outdoor points. The recovery of APs from air samples was increased by addition of ascorbic acid to the filters. 4-tert-butylphenol (4-t-BP), 4-tert-octylphenol (4-t-OP), and 4-nonylphenol (4-NP) were detected in both indoor and outdoor air. Their concentrations and detection frequencies were higher in indoor air than outdoor air. The maximum levels of 4-t-BP, 4-t-OP, and 4-NP in indoor were 387, 45.7, and 680 ng/m(3), respectively. 4-t-BP and 4-NP were detected with high frequencies (more than 97%) in indoor air samples. The concentrations of 4-t-BP, 4-t-OP, and 4-NP in indoor air were significantly correlated with room temperature (P < 0.01), and tended to be higher in newly built houses. The migration rates of APs from the floor, wall, and ceiling in the newly built house were higher in polyvinyl chloride coverings than in other materials. Practical Implications Alkylphenol ethoxylate (APE) are widely used surfactants in both industrial and domestic detergents. When these detergents are released into the environment, APE are biodegraded to the smaller chain ethoxylates and alkylphenols (APs). There are many reports about APs in aquatic environments because of their estrogenic effect on wildlife. In building materials, APs are used as antioxidant for polymer resins such as wall or floor coverings. Although APs has a lower vapor pressure, these agents are released into indoor air from the surface of polymer resins. This study surveyed concentrations of airborne AP in indoor air and outdoor air in Tokyo. In addition, to identify APs emission sources in a newly built house, migration tests of APs from interior surfaces to solid extraction disks were performed. PRACTICAL IMPLICATIONS: Alkylphenol ethoxylate (APE) are widely used surfactants in both industrial and domestic detergents. When these detergents are released into the environment, APE are biodegraded to the smaller chain ethoxylates and alkylphenols (APs). There are many reports about APs in aquatic environments because of their estrogenic effect on wildlife. In building materials, APs are used as antioxidant for polymer resins such as wall or floor coverings. Although APs has a lower vapor pressure, these agents are released into indoor air from the surface of polymer resins. This study surveyed concentrations of airborne AP in indoor air and outdoor air in Tokyo. In addition, to identify APs emission sources in a newly built house, migration tests of APs from interior surfaces to solid extraction disks were performed.     

Contamination of indoor air by toxic soil vapours: the effects of subfloor ventilation and other protective measures

A steady-state analytical model is derived for estimating the concentration of vapour-phase contaminants in indoor air in houses with subfloor voids, given the contaminant concentration in bulk soil. The model includes the key mechanisms of transport and dispersion—contaminant partitioning into the soil-vapour phase, molecular diffusion, suction flow, stack effect, and ventilation, including contaminant transport by ventilation flow between subfloor void and living space. Using the model, different construction styles are examined from the point of view of their resistance to ingress of soil gases. Model results indicate that indoor air concentration depends strongly on wind velocity and on geometrical parameters of void and living space. Worked examples for houses of different construction styles illustrate the effects of wind velocity and house parameters on the concentration of benzene in soil that would give rise to its maximum permissible concentration in indoor air. Brief consideration is also given to concrete raft foundations and clean cover systems.     

Evaluation of ventilation code requirements for building crawl spaces

Building ventilation code requirements for crawl spaces were reviewed from 1937 to today and though remain largely unchanged, provide designers and builders flexibility in moisture control methods. This study evaluates the current building ventilation code requirements for at-grade and below grade crawl space using computational fluid dynamic (CFD) software with experiment inputs. The research first tested the soil moisture evaporation rate from two monitored crawl spaces in Colorado, US, which produces an average moisture load of 13.75 grains/(ft²·h) (9.6g/(m²·h)) and a maximum load of 42.7 grains/(ft²·h) (29.8g/(m²·h)). The soil moisture evaporation rates identified align well in magnitude with those recorded in the literature, supporting the estimation method used. The experiment reveals that plastic ground cover can effectively reduce the moisture load from the soil by an average of 93%. The study then developed a CFD model of the monitored crawl space to assess the necessity and effectiveness of various ventilation code requirements. The space effective leakage area to the exterior was determined through field pressurization testing and CFD analysis to be approximately 0.26in.²/ft² of floor area. The CFD predictions, validated with the measured data, verify that the building code requirements for at-grade crawl spaces appear sufficient, but have limitations for below grade crawl spaces. Sealed crawl spaces perform better in humid climates, supporting previous research, and mechanical ventilation is justified for below grade crawl spaces only. The paper provides suggestions for the revisions to the current building code to recognize below grade underfloor spaces.     

A study on the potential of natural ventilation and cooling for large spaces in subtropical climatic regions

The potential of natural ventilation and cooling due to stack effects was investigated for large spaces with high ceilings. Different opening area ratios with respect to floor area were studied. Parameters of stack effects that consider floor heights were analyzed. Performance of natural ventilation was evaluated with cooling effects and indoor air quality for different months of the year. Three cities in northern, middle and southern Taiwan were used to represent typical subtropical weather types. It was found that opening ratio above 0.9％ is sufficient to provide fresh air to meet IAQ requirement. Two different temperature control strategies, fixed indoor temperature (FIT) and operative indoor temperature (OIT) were proposed and studied. A sensible cooling potential, f_pc, was proposed. Different levels of f_pc, namely, strong, medium, weak and not available were used to evaluate the number of days for which natural cooling, hybrid ventilation, mechanical air conditioning are to be applied to satisfy the cooling requirement. The research results presented can be used in the design of openings for large spaces, and also the air-conditioning control strategies for different seasons of the year.     

Spatial and temporal variability in VOC levels within a commercial retail building

A study was performed to characterize the concentration of dozens of volatile organic compounds (VOCs) at 10 locations within a single large building and track these concentrations over a 2-year period. The study was performed at a shopping center (strip mall) in New Jersey. A total of 130 indoor air samples were collected from 10 retail stores within the shopping center and analyzed for 60 VOCs by US EPA Method TO-15. Indoor concentrations of up to 55,100 microg/m(3) were measured for individual VOCs. The indoor/outdoor ratio (I/O) was as high as 1500 for acetone and exceeded 100 at times for various compounds, indicating that significant indoor air sources were present. A large degree of spatial variability was observed between stores within the building, with concentrations varying by three to four orders of magnitude for some compounds. The spatial variability was dependent on the proximity of the sampling locations to the indoor sources. A large degree of temporal variability also was observed for compounds emitted from indoor sources, but the temporal variability generally did not exceed two standard deviations (sigma). For compounds not emitted from indoor sources at significant rates, both the spatial and temporal variability tended to range within an order of magnitude at each location. PRACTICAL IMPLICATIONS: Many cross-sectional studies have been published where the levels of volatile organic compounds (VOCs) were measured in indoor air at one or two locations for houses or offices. This study provides longitudinal data for a commercial retail building and also addresses spatial variability within the building. The data suggest that spatial and temporal variability are important considerations for compounds emitted from indoor sources. Elevated concentrations were found in retail spaces with no apparent emission sources due to their proximity to other retail spaces with emission sources.     

The effect of different foundation systems on the fungal flora in the crawl space of a new wooden Japanese house

To establish novel preventive measures against damage of wooden houses by decay fungi with less chemical, we periodically monitored the fungal flora in two different foundation systems in the crawl space of an experimental Japanese house.     

Automobile proximity and indoor residential concentrations of BTEX and MTBE

Attached garages have been identified as important sources of indoor residential air pollution. However, the literature lacks information on (1) how the proximity of cars to the living area affects indoor concentrations of gasoline-related compounds, such as benzene; and (2) the origin of these pollutants, i.e., vapor or tailpipe emissions. We analyzed data from the Relationships of Indoor, Outdoor, and Personal Air (RIOPA) study to evaluate indoor (C_in) and outdoor (C_out) concentrations for 114 residences with cars either in an attached garage, a detached garage or carport, or without cars. Results indicate that single-family detached homes with cars in attached garages were affected the most by parked vehicles, followed by homes with vehicles in carports. Concentrations in homes with cars in detached garages were similar to those in residences without cars. Low ventilation rates exacerbated C_in in homes with attached garages. In general, the contribution from gasoline-related sources to indoor benzene and MTBE concentrations appeared to have been dominated by car exhaust, or by a combination of tailpipe and gasoline vapor emissions. Residing in a home with an attached garage could lead to benzene exposures that are an order of magnitude higher than exposures from commuting in a car in heavy traffic, with a risk of 17 excess cancers in a population of a million. Strategies to lower exposure to gasoline-related contaminants in homes include improving construction practices to prevent the infiltration of pollutants into the living quarters or incorporating detached garages.     

Analysis of One and Two-Story Single Family Home Fire Dynamics and the Impact of Firefighter Horizontal Ventilation

This paper describes experimental investigations on fire service ventilation practices in modern house geometries. Two houses were constructed inside a large fire facility. The first of two houses constructed was a one-story, 111.5 m², 3 bedroom, 1 bathroom house with 8 total rooms. The second house was a two-story 297.3 m², 4 bedroom, 2.5 bathroom house with 12 total rooms. The second house featured a modern open floor plan, two-story great room and open foyer. Fifteen experiments were conducted varying the ventilation locations and the number of ventilation openings. Ventilation scenarios included ventilating the front door only, opening the front door and a window near and remote from the seat of the fire, opening a window only and ventilating a higher opening in the two-story house. One scenario in each house was conducted in triplicate to examine repeatability. The results of these experiments examine potential occupant tenability and provide knowledge for the fire service for them to examine their horizontal ventilation standard operating procedures and training content. The fire dynamics resulting from ventilation practices such as ventilation near or remote from the seat of the fire and high versus low in relation to the fire are examined. Several other tactical considerations were developed utilizing the data from these experiments to provide specific examples of changes that can be adopted based on a departments current strategies and tactics. Such tactical considerations and a systems approach to fire service tactics should be investigated further.     

Addition of Olfs from Different Pollution Sources,determined by a Trained Panel

The purpose of this study was to predict how indoor air is perceived when polluted by different materials simultaneously. A panel of five trained judges was exposed to air polluted by each of 11 different single pollution sources. The panel was also exposed to 13 pair combinations of these single pollution sources and to one combination of five sources. The pollution sources comprised typical indoor building materials, materials from ventilation systems and other frequently occurring indoor pollution sources. The results indicate that the total sensory pollution load in a space may, as a first approximation, be predkted by simple addition of the olf values of the single sources.     

One-year Measurement of Indoor Climate and Energy Consumption of Super-insulated Houses in a Mild Climate Region of Japan

Two super-insulated houses were constructed near Sendai City in accordance with the Canadian R-2000 manual (Canadian Home Builders' Assoc., 1987). Shelter performance, thermal environment, air quality and energy consumption of these two houses were investigated for one year. The two super-insulated houses were very airtight compared with other houses. The one-year measurement of room temperature and humidity for one super-insulated house showed that the daily mean temperature for the dining-living room and the master bedroom was 15°C-20°C during the winter and 22°C-28°C during the summer. Absolute humidity for these rooms was less than 5 g/kg (DA) during the winter. The indoor environment of the two super-insulated houses during the heating season was more thermally comfortable, compared with that of ordinary houses in Japan. During the summer, the indoor temperature in these two houses was stable during the day and did not decrease at night even if the outdoor air temperature dropped. The CO₂ concentration in these two houses was lower than that of other airtight houses due to continuous mechanical ventilation. The space heating energy consumption for one super-insulated house was less than that of ordinary houses in Tohoku District in which only the living-dining room was heated.