Alireza Afshari | Danish Building Research Institute, AAU (original) (raw)
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Papers by Alireza Afshari
Sustainability, 2022
Mixing ventilation systems effectively improves thermal comfort in open-spaces due to adequate tu... more Mixing ventilation systems effectively improves thermal comfort in open-spaces due to adequate turbulent mixing of the cold stream with ambient air. This study introduces the concept of precision ventilation for achieving local thermal comfort in a mixing ventilation system. This precision ventilation system provides asymmetrical airflows from an active chilled beam (ACB) to each of the office occupants. These ACBs provide air velocities with different magnitudes and directions. To achieve different magnitudes and directions, JetCones are used to vary the airflow in different parts of the ACB. The performance of the precision ventilation system was analyzed using full-scale laboratory experiments and computational fluid dynamic (CFD) simulations. The full-scale laboratory experiments were conducted in a 4.2 m × 3 m × 2.8 m (L × W × H) thermal isolated room with an open-plan dual desk-chair setup. The jet-cones in the ACB unit were adjusted to throw the required amount of flow to the...
Sustainability, 2021
Nanofibre filters may offer new properties not available in commercial fibre filters. These inclu... more Nanofibre filters may offer new properties not available in commercial fibre filters. These include a higher surface area and the ability to include novel materials within the fibres. In addition the small size allows potential gains in performance due to the slip-flow phenomenon in which normal gas viscosity does not apply to objects smaller than the mean free path of the gas. We tested the properties of novel electrospun fibre filters generated from polyvinyl alcohol solutions, optionally embedded with nano-grains of photocatalytic TiO2 and activated charcoal. The tested materials exhibited pressure drops in the range of 195 Pa to 2693 Pa for a face velocity of 5.3 cm/s and a removal efficiency greater than 97% for 12–480 nm particles. Basis weights for the filters ranged from 16.6 to 67.6 g/m2 and specific surface areas ranged from 1.4 to 17.4 m2/g. Reactivity towards volatile organic compounds (VOCs) was achieved by irradiating the photocatalytic filters with ultraviolet light. ...
IOP Conference Series: Earth and Environmental Science, 2020
A variety of air filtration technologies are commercially available for reducing particles and ga... more A variety of air filtration technologies are commercially available for reducing particles and gaseous contaminants that may enter buildings from outside. According to the World Health Organization (WHO), there is an increasing range of adverse health effects linked to air pollution, at even-lower concentration of pollutants. This article presents a short literature overview of air filtration technologies, which focus on assessing their ability in removing both particles and gaseous compounds. The aim is to provide information about current research development of air filtration technologies as well as their advantages, limitations and performance in terms of removal efficiency, pressure drop and formation of by-products. Mechanical filters and electrostatic filters are efficiently used for the removal of particles. Photocatalytic oxidant and adsorbent air filters are commonly used for gas removal. These last two types of filters are not feasible for particles removal. Air filtratio...
Journal of building engineering, 2015
... Forskningscenter for Forebyggelse og Sundhed, Amtssygehuset i Glostrup Henrik N. Knudsen, Ali... more ... Forskningscenter for Forebyggelse og Sundhed, Amtssygehuset i Glostrup Henrik N. Knudsen, Alireza Afshari og Carsten M. Pedersen Statens Byggeforskningsinstitut John Christian Larsen og Elsa Nielsen Danmarks Fødevareforskning Miljøprojekt Nr. 1097 2006 Page 2. ...
Tess welcomed the committee members and guests to the annual meeting: 1.1 Reminded everyone of th... more Tess welcomed the committee members and guests to the annual meeting: 1.1 Reminded everyone of the nomination year ahead. 1.2 Highlighted the conference sessions of interest to this committee (Appendix 3). 1.3 Expressed appreciation to Esin Sultan Oguz and the Turkey Library Association for hosting the mid-year meeting, which was a great success. 2. Document check Completed. 3. Round table – Introduction and sharing of projects/work Each person took the time to introduce themselves and also included a brief update on a project, passion or piece of work they have undertaken in the last year.
To control the emission of pollutants from building materials, labelling systems have been introd... more To control the emission of pollutants from building materials, labelling systems have been introduced. Some of the systems combine measurements of volatile organic compounds according to 16000-9 and sensory evaluations. In Denmark, the sensory tests are performed by a minimum of 20 subjects. The subjects assess the air quality using a continuous acceptability scale and an odour intensity scale. In Germany the sensory evaluation system is being developed. The volumetric flow in the chambers is too low for direct sensory evaluation. Thus a system is developed to sample the air from air sampling bag. The air is evaluated by a panel of at least 10 persons using a reference scale. For the Finnish M1 label the sensory evaluations are performed by 5 to 10 subjects assessing air quality using a continuous acceptability scale and describing the odour using a list of odour profiles. The purpose of the present paper is to compare and discuss the sensory test procedures of the different labelli...
Tabel 2 Summarisk dokumentation af BSim-modellen for det fuldmurede hus i Rødvig.
This paper presents an investigation regarding a thermal comfort study carried out in an office b... more This paper presents an investigation regarding a thermal comfort study carried out in an office building located in Jönköping, Sweden. The particularity is that, in authors' knowledge, this is the first building equipped with a novel active beam system that operates a water loop with temperatures close to room temperature all year round. Indoor climate parameters such as air temperature and air velocity were measured at four heights in two locations within the occupied zone of a room in the building. Two measuring campaigns were performed: one in winter and one in summer. Both experiments lasted for a continuous period of 24 hours. The daily monitoring of the thermal environment showed that the room air temperature was between approximately 21 °C and 23 °C all year round. No significant vertical air temperature difference was noticed, and the draught rate was below 10% for most of the cases.
The present article is based on the post occupancy occupants' perception of indoor air quality of... more The present article is based on the post occupancy occupants' perception of indoor air quality of recently renovated 23 residential apartments in Copenhagen. The apartments are equipped with novel mechanical ventilation systems. The apartments can be categorised in four, according to the design of ventilation systems. The analysis in present article is based on occupants' perception of the temperature, indoor air quality and energy consumptions of their apartments. The study shows the perception of occupants of first six months of post occupancy. The study was carried out by conducting interviews with the tenants. 74% of the total occupants took part in the interviews. 83% of the interviewed occupants as an averaged spend more than 50% of their time inside their apartments. 37% of the total interviewed occupants were satisfied with the current performance of their apartments. Apparently the reason of dissatisfaction of occupants was the lack of maintenance of the HVAC systems. Another point raised by the occupants during the interviews was the missing provision of user control on ventilation system.
Sustainability, 2022
Mixing ventilation systems effectively improves thermal comfort in open-spaces due to adequate tu... more Mixing ventilation systems effectively improves thermal comfort in open-spaces due to adequate turbulent mixing of the cold stream with ambient air. This study introduces the concept of precision ventilation for achieving local thermal comfort in a mixing ventilation system. This precision ventilation system provides asymmetrical airflows from an active chilled beam (ACB) to each of the office occupants. These ACBs provide air velocities with different magnitudes and directions. To achieve different magnitudes and directions, JetCones are used to vary the airflow in different parts of the ACB. The performance of the precision ventilation system was analyzed using full-scale laboratory experiments and computational fluid dynamic (CFD) simulations. The full-scale laboratory experiments were conducted in a 4.2 m × 3 m × 2.8 m (L × W × H) thermal isolated room with an open-plan dual desk-chair setup. The jet-cones in the ACB unit were adjusted to throw the required amount of flow to the...
Sustainability, 2021
Nanofibre filters may offer new properties not available in commercial fibre filters. These inclu... more Nanofibre filters may offer new properties not available in commercial fibre filters. These include a higher surface area and the ability to include novel materials within the fibres. In addition the small size allows potential gains in performance due to the slip-flow phenomenon in which normal gas viscosity does not apply to objects smaller than the mean free path of the gas. We tested the properties of novel electrospun fibre filters generated from polyvinyl alcohol solutions, optionally embedded with nano-grains of photocatalytic TiO2 and activated charcoal. The tested materials exhibited pressure drops in the range of 195 Pa to 2693 Pa for a face velocity of 5.3 cm/s and a removal efficiency greater than 97% for 12–480 nm particles. Basis weights for the filters ranged from 16.6 to 67.6 g/m2 and specific surface areas ranged from 1.4 to 17.4 m2/g. Reactivity towards volatile organic compounds (VOCs) was achieved by irradiating the photocatalytic filters with ultraviolet light. ...
IOP Conference Series: Earth and Environmental Science, 2020
A variety of air filtration technologies are commercially available for reducing particles and ga... more A variety of air filtration technologies are commercially available for reducing particles and gaseous contaminants that may enter buildings from outside. According to the World Health Organization (WHO), there is an increasing range of adverse health effects linked to air pollution, at even-lower concentration of pollutants. This article presents a short literature overview of air filtration technologies, which focus on assessing their ability in removing both particles and gaseous compounds. The aim is to provide information about current research development of air filtration technologies as well as their advantages, limitations and performance in terms of removal efficiency, pressure drop and formation of by-products. Mechanical filters and electrostatic filters are efficiently used for the removal of particles. Photocatalytic oxidant and adsorbent air filters are commonly used for gas removal. These last two types of filters are not feasible for particles removal. Air filtratio...
Journal of building engineering, 2015
... Forskningscenter for Forebyggelse og Sundhed, Amtssygehuset i Glostrup Henrik N. Knudsen, Ali... more ... Forskningscenter for Forebyggelse og Sundhed, Amtssygehuset i Glostrup Henrik N. Knudsen, Alireza Afshari og Carsten M. Pedersen Statens Byggeforskningsinstitut John Christian Larsen og Elsa Nielsen Danmarks Fødevareforskning Miljøprojekt Nr. 1097 2006 Page 2. ...
Tess welcomed the committee members and guests to the annual meeting: 1.1 Reminded everyone of th... more Tess welcomed the committee members and guests to the annual meeting: 1.1 Reminded everyone of the nomination year ahead. 1.2 Highlighted the conference sessions of interest to this committee (Appendix 3). 1.3 Expressed appreciation to Esin Sultan Oguz and the Turkey Library Association for hosting the mid-year meeting, which was a great success. 2. Document check Completed. 3. Round table – Introduction and sharing of projects/work Each person took the time to introduce themselves and also included a brief update on a project, passion or piece of work they have undertaken in the last year.
To control the emission of pollutants from building materials, labelling systems have been introd... more To control the emission of pollutants from building materials, labelling systems have been introduced. Some of the systems combine measurements of volatile organic compounds according to 16000-9 and sensory evaluations. In Denmark, the sensory tests are performed by a minimum of 20 subjects. The subjects assess the air quality using a continuous acceptability scale and an odour intensity scale. In Germany the sensory evaluation system is being developed. The volumetric flow in the chambers is too low for direct sensory evaluation. Thus a system is developed to sample the air from air sampling bag. The air is evaluated by a panel of at least 10 persons using a reference scale. For the Finnish M1 label the sensory evaluations are performed by 5 to 10 subjects assessing air quality using a continuous acceptability scale and describing the odour using a list of odour profiles. The purpose of the present paper is to compare and discuss the sensory test procedures of the different labelli...
Tabel 2 Summarisk dokumentation af BSim-modellen for det fuldmurede hus i Rødvig.
This paper presents an investigation regarding a thermal comfort study carried out in an office b... more This paper presents an investigation regarding a thermal comfort study carried out in an office building located in Jönköping, Sweden. The particularity is that, in authors' knowledge, this is the first building equipped with a novel active beam system that operates a water loop with temperatures close to room temperature all year round. Indoor climate parameters such as air temperature and air velocity were measured at four heights in two locations within the occupied zone of a room in the building. Two measuring campaigns were performed: one in winter and one in summer. Both experiments lasted for a continuous period of 24 hours. The daily monitoring of the thermal environment showed that the room air temperature was between approximately 21 °C and 23 °C all year round. No significant vertical air temperature difference was noticed, and the draught rate was below 10% for most of the cases.
The present article is based on the post occupancy occupants' perception of indoor air quality of... more The present article is based on the post occupancy occupants' perception of indoor air quality of recently renovated 23 residential apartments in Copenhagen. The apartments are equipped with novel mechanical ventilation systems. The apartments can be categorised in four, according to the design of ventilation systems. The analysis in present article is based on occupants' perception of the temperature, indoor air quality and energy consumptions of their apartments. The study shows the perception of occupants of first six months of post occupancy. The study was carried out by conducting interviews with the tenants. 74% of the total occupants took part in the interviews. 83% of the interviewed occupants as an averaged spend more than 50% of their time inside their apartments. 37% of the total interviewed occupants were satisfied with the current performance of their apartments. Apparently the reason of dissatisfaction of occupants was the lack of maintenance of the HVAC systems. Another point raised by the occupants during the interviews was the missing provision of user control on ventilation system.