| 1. |
- Abdul Hamid, Akram, et al.
(author)
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Determining the impact of air-side cleaning for heat exchangers in ventilation systems
- 2020
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In: Building Services Engineering Research & Technology. - : SAGE Publications. - 0143-6244 .- 1477-0849. ; 41:1, s. 46-59
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Journal article (peer-reviewed)abstract
- Cleaning coils can be an efficient way to reduce the need for reparations and maintain the functionality of a ventilation system. This study builds upon existing knowledge concerning the contamination of heat exchangers. Through field measurements on coils and heat-recovery units, a laboratory experiment on a coil, and a generic calculation example, this study determines the impact of sustained contamination on heat-recovery units with regards to energy use. Field measurements made before and after cleaning of heat exchangers show an average increase in the pressure drop by 12% and decrease in the thermal exchange efficiency by 8.1% due to mass deposited on the surface of the heat exchangers. Results from a laboratory test show a correlation between the mass deposited on a coil and (1) the increase in pressure drop over the coil, as well as (2) a diminishing heat exchange. Accumulating contamination on heat-recovery units in residential and commercial buildings (over time) is then linked to increasing pressure drop and diminishing thermal efficiency. With models based on these links, energy loss over time is calculated based on a generic calculation example in a realistic scenario. Practical application : The results from this study emphasize the need for maintenance of buildings with ventilation systems with coils, but more so those with heat-recovery units. The presented field measurements and laboratory study correlate energy loss with sustained accumulation of contaminants on coils and heat-recovery units. These results should serve as a recommendation to property owners considering maintenance of such units in their buildings.
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| 2. |
- Abdul Hamid, Akram, et al.
(author)
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Determining the Impact of High Residential Density on Indoor Environment, Energy Use, and Moisture Loads in Swedish Apartments-and Measures for Mitigation
- 2021
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In: Sustainability. - : MDPI AG. - 2071-1050. ; 13:10
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Journal article (peer-reviewed)abstract
- Recently, there has been an increase in apartments with a large number of inhabitants, i.e., high residential density. This is partly due to a housing shortage in general but also increased migration, particularly in suburbs of major cities. This paper specifies issues that might be caused by high residential density by investigating the technical parameters influenced in Swedish apartments that are likely to have high residential density. Interviews with 11 employees at housing companies were conducted to identify issues that might be caused by high residential density. Furthermore, simulations were conducted based on extreme conditions described in the interviews to determine the impact on the energy use, indoor environmental quality, and moisture loads. In addition, the impact of measures to mitigate the identified issues was determined. Measures such as demand-controlled ventilation, increase of a constant ventilation rate, and moisture buffering are shown to reduce the risk for thermal discomfort, mold growth, and diminished indoor air quality; while still achieving a lower energy use than in a normally occupied apartment. The results of this study can be used by authorities to formulate incentives and/or recommendations for housing owners to implement measures to ensure good indoor environmental quality for all, irrespective of residential density conditions.
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| 3. |
- Abdul Hamid, Akram, et al.
(author)
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Evaluation of set points for moisture supply and volatile organic compounds as controlling parameters for demand controlled ventilation in multifamily houses
- 2014
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Conference paper (peer-reviewed)abstract
- The main purpose has been to evaluate existing set points (thresholds) and suggest proper set points, for the regulation of the air change rate in a demand controlled mechanical ventilation (DCV) system. The DCV is controlled by measurements in the supply and exhaust air of the vapor content and volatile organic compounds (VOCs) for each dwelling in multifamily houses. Results have been achieved through a literature review and laboratory tests. The threshold for the maximum ventilation rate (0.8 ac/h) should be set at 1000 ppm (CO2-eq.). Preferably, a minimum ventilation rate of 0.5 ac/h should be set with current thresholds (800-1000 ppm CO2-eq.). With a lower minimum ventilation rate (e.g. 0.1 ac/h) the lower threshold should be set at 450 ppm (CO2-eq). In order to deal with heavy moisture production the threshold for the moisture supply is suggested to be set at 3 g/m3.
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| 4. |
- Abdul Hamid, Akram
(author)
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Field Measurements for Verification of the Impact of Renovation and Maintenance Measures on Buildings : - regarding Energy Efficiency, Indoor Environment and Moisture Safety
- 2019. - 1
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Doctoral thesis (other academic/artistic)abstract
- Renovating the European building stock has for almost two decades been a matter of importance to the European Union. Reduction of energy use for existing buildings can be achieved through applying energy efficiency renovation measures. Besides this, there is quite a large renovation need in Sweden due to building materials and services reaching (or having passed) the end of their service life.Incorrectly implemented, renovation measures can have negative impacts on the state of the building, and so can the lack of maintenance measures. In order to avoid negative outcomes, impacts of possible renovation and maintenance measures need to be evaluated. It is also important to be able to predict these impacts and therefore important to acquire data on them, but also more knowledge on how to isolate the impacts of such measures through field measurements.This thesis aims to assess the impact of relevant and applicable renovation or maintenance measures for buildings in temperate climates, primarily through field measurements. This thesis also aims to illuminate the process of field measurements for acquiring data for the assessment of renovation and maintenance measures. The empirical base for this has included five case studies on renovation or maintenance measures that are relevant for Swedish buildings, and a literature review. In order to illuminate the process of field measurements for the assessment of the impact that renovation and maintenance measures has on a building, this thesis has analyzed the research procedure in five case studies that have included such assessments. These case studies included measures that impacted on the energy use, the indoor environmental quality, and/or the moisture safety of a building.The thesis compares the setups of the field measurements in the case studies, discusses the details of the field measurements, the limitations in each study and the consequences thereof, and the knowledge that was gained through the analyses that were conducted. This empirical data, gained from these analyses, formed the basis for the illumination of the overall method for the assessment of renovation and maintenance measures through field measurements.The results in the included case studies show that the measures that have been evaluated have a beneficial impact on the energy use, and some also on the indoor environment. However, it is important to consider possible risks with implementing the measures in order to avoid negative outcomes. The case studies show that it is possible to determine the impact through field measurements, with accuracy. The analysis of the procedures in the case studies in this thesis shows that different measurement setups require different types of analyses in order to determine the impact of the measure. If field measurements are conducted on an object (e.g. a building) before and after the implementation of a measure, control parameters should be measured simultaneously in order to determine the impact of changes in these parameters on the object and thereby isolate the impact of the measure. If measurements are conducted solely after the implementation of the measure, simultaneous measurements should be conducted on a control object, that is comparable to the object on which the measure has been implemented (the main object) and preferably has not undergone any changes during the study. The combination of the case studies shows that the design of the field measurements is often based on a hypothesis. The design considers limitations of the case study, possible impact of control parameters, if it is possible to conduct measurements on a control object, and if it is possible to retrieve data from other sources. The combination of the case studies also shows that, most likely, a deviation (e.g. sensor failures) will occur, or a limitation will exist, which will require supplementary analyses to be conducted in order to answer the hypothesis and/ or other questions related to the determination of the impact of the measure.
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| 5. |
- Abdul Hamid, Akram, et al.
(author)
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Hygrothermal assessment of internally added thermal insulation on external brick walls in Swedish multifamily buildings
- 2017
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In: Building and Environment. - : Elsevier BV. - 0360-1323. ; 123, s. 351-362
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Journal article (peer-reviewed)abstract
- Proper and efficient renovation requires understanding the behavior of existing buildings and of different building materials. Analyzing hygrothermal measurements in two case studies, one with and the other without an internally added thermal insulation system, enabled us to identify factors of critical importance for further assessment through simulations, and to validate a hygrothermal simulation model of a solid brick masonry wall, a model used then to assess internally added thermal insulation systems of different types. A mold resistance design (MRD) model shows that, in connection with all internally added thermal insulation systems, the risk of mold growth is appreciable when brought on by solar driven vapor from the exterior. This, if biological material is present in either of two critical areas, those of the boundary between the thermal insulation and either 1) the existing masonry wall, or 2) the exterior surface of an internally added vapor barrier. Furthermore, assessments of corrosion risks are conducted for two critical placements of the bed-joint reinforcement. At a depth of 30 mm from the exterior surface, the corrosion risk was found to be less with use of capillary-active vapor-open systems than when no thermal insulation was employed, other systems increase the corrosion risk. At a depth of 90 mm, all thermal insulation systems increase the corrosion risk. Excluding precipitation uptake eliminates all risks, showing that this is the most crucial factor. Solutions that limit this uptake or increase the drying-out rate should thus be considered beneficial.
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| 6. |
- Abdul Hamid, Akram, et al.
(author)
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Impact of high residential density on the building technology, HVAC systems, and indoor environment in Swedish apartments
- 2020
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In: E3S Web of Conferences. Volyme 172, 2020.. - : EDP Sciences. ; 172
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Conference paper (peer-reviewed)abstract
- During the last few years, there has been an increased number of overcrowded apartments, due to increased migration but also housing shortage in general, particularly in the suburbs to major cities. The question is how the indoor environment in these apartments is affected by the high number of persons and how the problems related to high residential density can be overcome. This paper aims to specify the problem by investigating and analysing the technical parameters influenced by residential density in Swedish apartments built between 1965-1974. To map the situation, 11 interviews with employees at housing companies were conducted. Based on extreme conditions described in the interviews, simulations of the indoor climate and moisture risks at some vulnerable parts of constructions were made. Simulations were focused on moisture loads and CO2 concentrations as functions of residential density and ventilation rate. Finally, measures to combat problems associated to overcrowding are suggested. The aim is that the results should be used by authorities to formulate incentives and/or recommendations for housing companies to take actions to ensure a good indoor environment for all, irrespective of residential density conditions. © The Authors.
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| 7. |
- Abdul Hamid, Akram, et al.
(author)
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Literature review on renovation of multifamily buildings in temperate climate conditions
- 2018
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In: Energy and Buildings. - : Elsevier BV. - 0378-7788. ; 172, s. 414-431
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Research review (peer-reviewed)abstract
- In Sweden, approximately 1.4 million dwellings were built 1946–1975. Today, a considerable part of these are in need of renovation for various reasons. Research results, as well as experiences and outcomes from renovation projects could facilitate in performing more efficient renovations. As an aid for further research, this paper aims to compile and review relevant literature that may support in choosing a renovation strategy as well as decisions on renovation measures. The focus of this paper is research on status determinations, renovation strategies and renovation measures. Differences and similarities within these areas are presented through the analysis of 234 relevant references. The results show that renovation of multifamily buildings in temperate climate conditions is widely researched. The included research has a strong energy focus, and while other aspects of renovation are researched as well, they are not as strongly represented. Status determinations are often based on data from national databases that include useful information that could help alleviate decision making in the renovation process. This study suggests that future research should be conducted on the effect of such databases on the renovation process. This study also shows that there are numerous renovation strategies, and while there are both in-depth and broader strategies, these are seldom connected. Finally, there are many references evaluating various effects of the application of renovation measures, but some effects and measures are more widely researched than others. This study lays a strong foundation for further in-depth research on the reviewed articles, reports, and theses.
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| 8. |
- Abdul Hamid, Akram, et al.
(author)
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Measuring the impact of MVHR on the energy efficiency and the IEQ in multifamily buildings
- 2019
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In: Energy and Buildings. - : Elsevier BV. - 0378-7788. ; 195, s. 93-104
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Journal article (peer-reviewed)abstract
- Renovating and improving the current building stock is a matter of both need and importance. In order to know if the implemented renovation measure has had an impact on the building as a system it is important to verify the impact through measurements. The aim of this project is to isolate the impact of a measure on the energy efficiency of a building as well as the indoor environmental quality. This, through detailed measurements that enable the exclusion of the impact of other factors that might affect the energy use. For this reason a mechanical ventilation system with heat recovery was installed in two apartment buildings and measurements were conducted before and after installation. Measurements were also conducted in two almost identical reference buildings, that were used as a control group for the experiment. Together with acquired data for the surrounding climate, measurements were conducted on 1)the district heat carriers to and from the buildings, 2)the temperature and relative humidity in the apartments, 3)the global horizontal radiation on site, and 4)the temperature outdoors. A survey was also conducted with the inhabitants for the assessment of the impact on the perceived indoor environmental quality. Correcting for the outdoor temperature only, a yearly reduction by 22% and 24% is achieved in the affected buildings. Changes in the global horizontal radiation clearly impact the results, however, can not be corrected for. By using the control group as a reference, further corrections can be made and the energy reduction might be determined to 15% and 34%, instead of 22% and 24% respectively.
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| 9. |
- Abdul Hamid, Akram
(author)
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Method for evaluation of renovation measures with regards to moisture and emission loads : Based on risk assessments
- 2017
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Licentiate thesis (other academic/artistic)abstract
- Renovating the European building stock has for almost two decades been a matter of importance. For Sweden, it is important to renovate its multifamily buildings in order to achieve a reduced energy use, but also because renovation is needed due to building materials and services reaching (or having passed) the end of their life span. In order to renovate properly, renovation measures must be implemented correctly to avoid negative impact on the building materials and the indoor environment. For this purpose, renovation measures need to be evaluated with regards to moisture and emission loads, and the risks related to these. This thesis has developed a realistically applicable method for this type of evaluation, called RememberL, and tests RememberL on two renovation measures as case studies. Through laboratory tests, in-field measurements, building performance simulations, hygrothermal simulations and surveys, the renovation measures are evaluated according to the methodology. RememberL thereby yields useful results for understanding the impact that these methods have on building materials and the indoor environment and vice versa. Furthermore, through the application of RememberL on these case studies, it is further developed to a method that proves flexible through several alternatives.
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| 10. |
- Abdul Hamid, Akram, et al.
(author)
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The impact of a DCV-system on the IAQ, energy use, and moisture safety in apartments - a case study
- 2022
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In: International Journal of Ventilation. - : Informa UK Limited. - 1473-3315 .- 2044-4044. ; 21:1, s. 35-52
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Journal article (peer-reviewed)abstract
- A novel DCV-system controls the air-change rate for each apartment in multifamily buildings based on two indoor air parameters: 1) the moisture load (supply), and 2) volatile organic compounds. With a central fan, but decentralized control boxes placed outside each apartment, the system controls the air-change rate for each apartment. This paper’s main aim is to determine the potential of this DCV-system, through a case study, to: 1) achieve good IAQ, 2) handle the moisture loads appropriately, and 3) achieve good energy efficiency in multifamily buildings. Furthermore, the paper aims to assess the possibility to achieve good IAQ by validating the DCV-system’s VOC-controls through measurements of CO2 in apartments. Field measurements show that the system responds appropriately to apartment-specific loads, and that acceptable emission and moisture loads are achieved in most apartments in the case study. The impact that the system has on the energy use was assessed through calculations based on the field measurements. The calculations show that the DCV-system saves energy used for heating the supply-air by 86% in comparison to a mechanically balanced ventilation system without heat recovery, and 22% in comparison to the same system but with heat recovery.
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