Natural radioactivity of granites used as building materials

Sixteen kinds of different granites, used as building materials, imported to Greece mainly from Spain and Brazil, were sampled and their natural radioactivity was measured by gamma-ray spectrometry. The activity concentrations of (238)U, (226)Ra, (232)Th and (40)K of granites are presented and compared to those of other building materials as well as other granite types used all over the world. In order to assess the radiological impact from the granites investigated, the absorbed and the effective doses were determined. Although the annual effective dose is higher than the limit of 1mSvy(-1) for some studied granites, they could be used safely as building materials, considering that their contribution in most of the house constructions is very low. An attempt to correlate the relatively high level of natural radioactivity, shown by some of the granites, with their constituent radioactive minerals and their chemical composition, was also made.     

Toxicity of building materials: a key issue in sustainable construction

To avoid the use of toxic building materials is one of the principles of sustainable construction. However and contrary to general beliefs, current residential buildings frequently contain many toxic building materials, some of which even comply with legal regulations. Part of the problem is because architects and civil engineers have no form of knowing the toxicity of building materials. The other part is economically related. Some regulations about toxicity limits are influenced by economic reasons. For instance, although scientific evidence about the toxicity of lead plumbing has existed for quite some time, legal regulations avoid imposing very tight thresholds because of the cost of lead pipe substitution (in Europe that could cost almost 200,000 million euros). It is then no surprise to see that the related Directive (98/83/CE) established a 15-year delay period before the 10 μg/l lead content threshold is enforced. This paper discusses some cases of toxic building materials by reviewing previously published work, it also covers the emission of volatile organic compounds from paints and varnishes, the toxicity of impregnating agents, materials that release toxic fumes during a fire, asbestos-based materials, radioactive materials and lead plumbing.     

Photon attenuation, natural radioactivity content and radon exhalation rate of building materials

High concentrations of natural radionuclides in building materials can result in high dose rates indoors, from both internal and external exposure. In dose calculations, the main radionuclides of interest are 226Ra, 232Th and 40K. Usually much attention is paid to 226Ra due to 222Rn exhalation and the subsequent internal exposure. Other radionuclides of the uranium series such as 238U and 210Pb, emitting low energy photons are not usually determined and an assumption of radioactive equilibrium is made. The above assumption is seldom checked mainly because of the difficulties in the gamma-spectroscopic analysis of low energy photons. For the determination of radionuclides emitting low-energy photons, in samples like building materials where intense self-absorption of the photons exists, a method for self-absorption correction has been developed. The method needs as input the linear attenuation coefficient mu for the material under analysis. This paper presents: 1. Correlations in the form mu = f(rho,E) developed for the estimation of the linear attenuation coefficient mu (cm(-1)), as a function of the material packing density p (g cm(-3)) and the photon energy E (keV), for building materials as well as other materials of environmental importance. 2. Gamma-spectroscopic analysis techniques used for the determination of 238U, 226Ra, 210Pb, 232Th and 40K in environmental samples, together with the results obtained from the analysis of building materials used in Greece, and industrial by-products used for the production of building materials. Among the techniques used, one is based on the direct determination of 226Ra and 235U from the analysis of the multiplet photopeak at approximarely186 keV. 3. Results from radon exhalation measurements of building materials such as cement and fly-ash and building structures conducted in the radon chambers in our Laboratory. Based on the above results, dosimetric calculations are also reported.     

Stakeholder requirements for building energy efficiency in mass housing delivery: the House of Quality approach

Threats of climate change and future energy price uncertainty have led to a global debate on energy efficiency, particularly the energy efficiency of housing projects. This serious global problem calls for improvement in energy efficiency from all sectors, especially the building sector which is considered a major energy consumer. Adoption of energy efficiency design practices in the housing sector has been perceived to have a significant potential to contribute greatly to the sustainable building process. Additionally, most studies indicate that the understanding and integration of stakeholder requirements has an enormous potential towards increasing the sustainability perspectives that relate to social, environmental, economic and technical issues of buildings. However, there is enough evidence from several studies suggesting a lack of common perspective on stakeholder requirements towards building energy efficiency (BEE) in housing development. Hence it is argued that stakeholders’ alignment for energy efficiency improvement is crucial and a fundamental challenge that needs to be addressed if the goal of energy use reduction in buildings is to be achieved. The aim of this paper is to identify the important building energy requirements among stakeholders of mass housing projects and their impact on technical characteristics of mass housing projects. Through a survey of building industry stakeholders and using the House of Quality model for analysis of the data obtained, the study identified five (5) most rated BEE stakeholders’ requirements in respect of housing development. The study gives a new insight into the considerations of building stakeholders regarding energy efficiency. This insight is useful towards achieving sustainable building solutions that meet the sustainability features of housing development in Ghana and other countries with similar energy and housing challenges.     

Indigenous African building techniques and the prospects for sustainable housing and environmental development

In this paper, sustainability is examined as one of the objectives of enabling man in a preserved, efficient and enduring world environment. Thus, sustainable housing and environmental development is conceptualized as a building or shelter provided through judicious, selective sourcing, processing and use of building materials to satisfy current shelter needs while ensuring quality environment and adequate resources for the future generations in satisfying theirs. To stimulate orderly academic debate, the paper proposes five major factors of sustainability. They include climatic sustainability factor, ecological sustainability factor, economics and affordability sustainability factor, social sustainability factor and cultural sustainability factor. The sustainability attributes of each factor are highlighted, and the criteria for the selection of building materials to satisfy the attributes are commended.     

A study about remedial measures to reduce 222Rn concentration in an experimental building

Radon gas emanating from underground can spread to adjoining closed areas. It can concentrate and reach levels which represent a risk to people's health. It is well known that radon presence in most areas depends mainly on the area's geological features. Indoor radon concentrations further depend on the type of structure, construction materials and the technology used for the building. Therefore, indoor radon monitoring is of primary importance for deciding whether remedial measures are to be adopted for reducing harmful concentrations. This approach has been tried by measuring radon concentration in an experimental building situated in Milan (Italy). This building situated in a geological area that is considered at low radon risk. The results were obtained after analysing radon concentration in indoor rooms, crawl spaces, soil gas and in the atmosphere outside and by measuring before and after adoption of remedial measures. The study shows that improper building design can give rise to higher indoor radon accumulation even in an area of poor radon exhalation. Furthermore, the results enable quantification of the effectiveness of the remedial measures.     

Setting up the criteria and credit-awarding scheme for building interior material selection to achieve better indoor air quality

Methods, standards, and regulations that are aimed to reduce indoor air pollution from building materials are critically reviewed. These are classified as content control and emission control. Methods and standards can be found in both of these two classes. In the regulation domain, only content control is enforced in some countries and some regions, and asbestos is the only building material that is banned for building use. The controlled pollutants include heavy metals, radon, formaldehyde, and volatile organic compounds (VOCs). Emission rate control based upon environment chamber testing is very much in the nature of voluntary product labeling and ranking, and this mainly targets formaldehyde and VOC emissions. It is suggested that radon emission from building materials should be subject to similar emission rate control. A comprehensive set criteria and credit-awarding scheme that encourages the use of low-emission building material is synthesized, and how this scheme can be practiced in building design is proposed and discussed.     

Indoor air pollution due to organic gases and vapours of solvents in building materials

The emission of organic gases and vapours of solvent type from 42 commonly used building materials was measured under standard atmospheric conditions. An average of 22 compounds was found in the air around each building material, and the total concentration of gases and vapours was from 0.01 to 1410 mg/m³. The average arithmetic emission rate was 9.5 mg/m² h, and 52 different compounds were identified. A mathematical model was established for the indoor air concentrations of pollutants originating from building materials. The model was tested on three model rooms constructed from the materials investigated. The calculated total air concentrations of gases and vapours in the three rooms ranged from 1.6 to 23.6 mg/m³, and the number of compounds in the air from 23 to 32. These concentrations and number of compounds did not differ from those found in actual rooms similar in size and construction to the model rooms. The risks of health effects due to the compounds identified from the building materials were investigated, and criteria for future air quality standards are discussed. It is concluded that the possibility of negative health effects cannot be neglected, especially not for the more sensitive minority of the general population.     

Proposing of new building scheme and composite towards global warming mitigation for Malaysia

The building sector has been regarded as a potential sector where there is large capacity to reduce the climate change effect. This study has proposed solutions to mitigate environmental impacts and achieve low CO₂ emission from residential sector. Therefore, full life cycle assessment (LCA) has been run to assess the CO₂ emission and its effect on the atmosphere and climate change. Based on the result, timber scheme is the best choice due to releasing less CO₂ emissions to the atmosphere. However, house builders in Malaysia have almost completely neglected timber as a building material, with timber use as building components reduced to 5%. In this study, LCA Software was used to assess CO₂ emissions from different wall construction. The alternative building scheme has been made by reinforce steel stud, wooden beam and timber wall (S8) to improve the scheme deficiency while releasing less CO₂ emissions compared to other schemes. Therefore, S8 has a decreased CO₂ effect by 85% less than precast concrete frame and 90% less than brick over their lifetime. (S8) increased the load bearing compared to conventional timber beam. Thus, new scheme S8 could be replaced by current scheme and promote more adjustable scheme for Malaysian housing.     

Assessment of natural radiation exposure and radon exhalation from building materials in Greece

In controlling the natural radiation exposure for the residents of dwellings, it is necessary to determine the levels of natural radioactivity (external exposure) and radon exhalation rate (internal exposure) from building materials. Using a high-resolution gamma ray spectrometry system, the activity concentration of natural radionuclides was measured. The radon exhalation rate was measured by hermetically closing the sample in a container and following the radon activity growth as a function of time. Three different methods were applied in order to find the most appropriate, i.e. that with the less uncertainty for the less exposure time. Typical building materials were analyzed in order to examine the external and internal exposures. In addition, the total annual effective dose was evaluated for the residents of a typical Greek dwelling.     

Symptoms prevalence among office workers of a sealed versus a non-sealed building: Associations to indoor air quality

ObjectivesAn increasing number of complaints related to time spent in artificially ventilated buildings have been progressively reported and attributed, at least in part, to physical and chemical exposures in the office environment. The objective of this research was to investigate the association between the prevalence of work-related symptoms and the indoor air quality, comparing a sealed office building with a naturally ventilated one, considering, specially, the indoor concentration of TPM, TVOCs and the main individual VOCs.MethodsA cross-sectional study was performed to compare the prevalence of sick building syndrome (SBS) symptoms among 1736 office workers of a sealed office building and 950 of a non-sealed one, both in Rio de Janeiro's downtown. The prevalence of symptoms was obtained by a SBS standardized questionnaire. The IAQ of the buildings was evaluated through specific methods, to determine the temperature, humidity, particulate matter and volatile organic compound (VOC) concentrations.ResultsUpper airways and ophthalmic symptoms, tiredness and headache were highly prevalent in both buildings. Some symptoms were more prevalent in the sealed building: “eye dryness” 33.3% and 27.1% (p: 0.01); “runny nose” 37.3% and 31.3% (p: 0.03); “dry throat” 42% and 36% (p: 0.02); and “lethargy” 58.5% and 50.5% (p: 0.03) respectively. However, relative humidity and indoor total particulate matter (TPM) concentration as well as total volatile organic compounds (TVOCs) were paradoxically greater in the non-sealed building, in which aromatic compounds had higher concentration, especially benzene. The analysis between measured exposure levels and resulting symptoms showed no association among its prevalence and TPM, TVOCs, benzene or toluene concentration in none of the buildings.ConclusionsOther disregarded factors, like undetected VOCs, mites, molds and endotoxin concentrations, may be associated to the greater prevalence of symptoms in the sealed building.     

Radon exhalation from building materials for decorative use

Long-term exposure to radon increases the risk of developing lung cancer. There is considerable public concern about radon exhalation from building materials and the contribution to indoor radon levels. To address this concern, radon exhalation rates were determined for 53 different samples of drywall, tile and granite available on the Canadian market for interior home decoration. The radon exhalation rates ranged from non-detectable to 312 Bq m⁻² d⁻¹. Slate tiles and granite slabs had relatively higher radon exhalation rates than other decorative materials, such as ceramic or porcelain tiles. The average radon exhalation rates were 30 Bq m⁻² d⁻¹ for slate tiles and 42 Bq m⁻² d⁻¹ for granite slabs of various types and origins. Analysis showed that even if an entire floor was covered with a material having a radon exhalation rate of 300 Bq m⁻² d⁻¹, it would contribute only 18 Bq m⁻³ to a tightly sealed house with an air exchange rate of 0.3 per hour. Generally speaking, building materials used in home decoration make no significant contribution to indoor radon for a house with adequate air exchange.     

Radionuclide content of building materials and associated gamma dose rates in Egyptian dwellings

Studies have been carried out to determine the natural radioactivity in some building materials (bricks, tiles, marble and ceramics) and their associated radiation hazard. The radioactivity concentrations of ²²⁶Ra ²³²Th and ⁴⁰K were measured using a gamma spectrometer with a Hp–Ge detector. The activities of ²³⁸U and ²³⁴U were measured using an alpha-spectrometer with a surface barrier detector after applying a radiochemical procedure. The ²³⁴U/²³⁸U isotopic ratios were calculated. The radium equivalent activities and the radiation hazard index associated with the natural radionuclides were calculated. A computer program was developed and applied to calculate the dose rate a person will receive from the walls of a room constructed from the studied building materials.     

Guidelines for Nordic building regulations regarding indoor air quality

A subcommittee of the Nordic Committee for Building Codes has released guidelines for building regulations regarding indoor air quality, especially concerning ventilation. The main features of the guidelines, such as acceptable outdoor air quality for ventilation and minimum outdoor air flows for dwellings and offices, are presented and discussed. Mechanical ventilation is, in principle, required in all buildings including dwellings, due to the requirement of a minimum outdoor air change of 0.5 h⁻¹ and the normal highly airtight nature of new buildings. The guidelines are a basis for designing energy-efficient buildings while maintaining an indoor air quality which provides acceptable comfort and does not impair health.     

Analysis of building environment assessment frameworks and their implications for sustainability indicators

Green construction is gaining increasing attention in the global context. However, the construction of sustainable green buildings and environments involves different tools and systems and diverse perspectives. Therefore, the development of environmental assessment tools is an important task for managing green housing and green building projects. In this paper, we discuss the benefits, limitations, and future directions of the assessment framework. There are four characteristics of building environmental assessment, i.e., comprehensiveness, design guideline, signaling, and communication tools, which afford both benefits and limitations. We illustrate the role of the assessment framework as a hub promoting integration of diverse knowledge, as a design guideline encouraging better design and action, as signaling environmentally friendly design and action, and as a communication tool. On the other hand, there are limitations, such as the use of a mixture of quantitative and qualitative measures, ambiguity of weighing, lack of financial evaluation, and lack of involvement of diverse disciplines and stakeholders. To develop an effective assessment framework, the following three factors must be considered: knowledge, power, and implementation. We propose that knowledge innovation, a credible approach for a salient solution, and collective action represent the future challenges of the assessment framework.     

Quantifying the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building

Improper natural ventilation practices may deteriorate indoor air quality when in close proximity to roadways, although the intention is often to reduce energy consumption. In this study, we employed a CFD-based air quality model to quantify the impact of traffic-related air pollution on the indoor air quality of a naturally ventilated building. Our study found that the building envelope restricts dispersion and dilution of particulate matter. The indoor concentration in the baseline condition located 10 m away from the roadway is roughly 16–21% greater than that at the edge of the roadway. The indoor flow recirculation creates a well-mixed zone with little variation in fine particle concentration (i.e., 253 nm). For ultrafine particles (< 100 nm), a noticeable decrease in particle concentrations indoors with increasing distance from the road is observed due to Brownian and turbulent diffusion. In addition, the indoor concentration strongly depends on the distance between the roadway and building, particle size, wind condition, and window size and location. A break-even point is observed at D′ ~ 2.1 (normalized distance from the roadway by the width of the road). The indoor particle concentration is greater than that at the highway where D′ < 2.1, and vice versa. For new building planning, the distance from the roadway and the ambient wind condition need to be considered at the early design stage whereas the size and location of the window openings, the interior layout, and the placement of fresh air intakes are important to the indoor air quality of existing buildings adjacent to roadways.     

Measurement of natural radioactivity in building materials in Qena city, Upper Egypt

Building materials cause direct radiation exposure because of their radium, thorium and potassium content. In this paper, samples of commonly used building materials (bricks, cement, gypsum, ceramics, marble, limestone and granite) in Qena city, Upper Egypt have been collected randomly over the city. The samples were tested for their radioactivity contents by using gamma spectroscopic measurements. The results show that the highest mean value of (226)Ra activity is 205+/-83 Bqkg(-1) measured in marble. The corresponding value of (232)Th is 118+/-14 Bqkg(-1) measured in granite. For (40)K this value is (8.7+/-3.9)x10(2) Bqkg(-1) measured in marble. The average concentrations of the three radionuclides in the different building materials are 116+/-54, 64+/-34 and (4.8+/-2.2)x10(2) Bqkg(-1) for (226)Ra, (232)Th and (40)K, respectively. Radium equivalent activities and various hazard indices were also calculated to assess the radiation hazard. The maximum mean of radium equivalent activity Ra(eq) is 436+/-199 Bqkg(-1) calculated in marble. The highest radioactivity level and dose rate in air from these materials were calculated in marble.     

Natural radionuclide content in building materials and gamma dose rate in dwellings in Cuba

An extensive research project to investigate the radioactive properties of Cuban building materials was carried out because there is a lack of information on the radioactivity of such materials in Cuba. In the framework of this project 44 samples of commonly used raw materials and building products were collected in five Cuban provinces. The activity concentrations of natural radionuclides were determined by gamma ray spectrometry using a p-type coaxial high purity germanium detector and their mean values were in the ranges: 9-857Bqkg(-1) for (40)K; 6-57Bqkg(-1) for (226)Ra; and 1.2-22Bqkg(-1) for (232)Th. The radium equivalent activity in the 44 samples varied from 4Bqkg(-1) (wood) to 272Bqkg(-1) (brick). A high pressure ionisation chamber was used to measure the indoor absorbed dose rate in 543 dwellings and workplaces in five Cuban provinces. The average absorbed dose rates in air ranged from 43nGyh(-1) (Holguín) to 73nGyh(-1) (Camagüey) and the corresponding population-weighted annual effective dose due to external gamma radiation was estimated to be 145+/-40microSv. This value is 51% lower than the effective dose due to internal exposure from inhalation of decay products of (222)Rn and (220)Rn and it is 16% higher than the calculated value for the typical room geometry of a Cuban house.     

Experimental investigation of gamma-ray attenuation in Jordanian building materials using HPGe-spectrometer

The capabilities of some building materials used in Jordan to attenuate gamma radiation were tested. Measurements of the attenuation coefficients of limestone, bricks and concrete have been carried out using a HPGe-spectrometer. Narrow beam technique was used, with a multiple gamma radiation source of different energy lines. Results indicate that variations in the attenuation coefficient for all limestone samples, at the same energy line, are within the experimental uncertainties. On the basis of the results achieved, an empirical formula mu(m)=AE(-0.44) was proposed to calculate attenuation at various incident energies. Limestone of average thickness 7cm was found to stop 75% of a gamma beam of energy 662keV. Meanwhile a brick of effective thickness 7cm was found to stop 60% of the same beam. The total attenuation coefficient of concrete calculated at 1333keV was 11.2m(-1), which is less than that of limestone and bricks.     

Natural radioactivity and radon exhalation in building materials used in Italian dwellings

Forty-two samples of building materials commonly used in Italian dwellings were surveyed for natural radioactivity. External (gamma), as defined and used by the European Commission, and internal (alpha) hazard indexes were calculated and radon specific exhalation rate and emanation fraction were measured. The accumulation method, by using the E-PERM electret ion chambers, was employed to determine specific exhalation rates of 222Rn. Several of the materials had hazard indexes that exceeded the European Commission limit values. However, it was evident that limit values for internal hazard indexes set based on Rn emanation should take into account the properties and use of the materials. For example, Rn emanation from basalt and glazed tiles was substantially lower than the Rn emanation from other materials with similar hazard indexes. Clearly there is need for improved guidelines and regulations in this area.