| 11. |
- Cholewa, Tomasz, et al.
(författare)
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Heat cost allocation in buildings : Possibilities, problems and solutions
- 2020
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Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 31, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- The individual heat cost allocation is one of the recent topics which is well-known not only for the possibility of increasing the energy efficiency but also for the related problems. However, there is no comprehensive work where the main problems are shown and adequate solutions are proposed. This article presents the main aspects which are important in the area of heat cost allocation. Firstly, the policy issues were underlined and the recommendations for the introduction of general rules for heating costs allocation at the level of a given country were provided. Secondly, the main possibilities, problems and solutions connected to the devices and methods for heat cost allocation were introduced. Then, the energy savings obtained using heat cost allocation were shown on the example of long term field research (8 heating seasons) carried out for six residential buildings, where heat cost allocators were uninstalled. Lastly, comprehensive recommendations were provided, the introduction of which will allow to minimizing the problems connected with heat cost allocation and maximizing the energy savings while maintaining the thermal comfort in the heated rooms.
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| 12. |
- Dabaieh, Marwa, et al.
(författare)
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Building Performance and Post Occupancy Evaluation for an off-grid low carbon and solar PV plus-energy powered building : A case from the Western Desert in Egypt
- 2018
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Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 18, s. 418-428
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Tidskriftsartikel (refereegranskat)abstract
- Current trends in energy supply and use within the building sector in Egypt are patently unsustainable and uneconomical; they are not environmentally and sometimes not even socially viable. Renewable energy has recently started to attract considerable attention as a future energy source. After major problems with electricity blackouts the photovoltaic (PV) market, in particular, has been growing significantly in Egypt over the last 5 years. This study was conducted to develop an evaluation method to assess the potential of applying passive design and low carbon and construction strategies together with PV systems for electricity power supply. A one year Building Performance and Post Occupancy Evaluation was carried out for a selected case study in Baharia, Egypt using records of energy use, demand profiles, and monitored thermal behaviour in indoor environments, together with a review of occupants’ satisfaction. The outcome of this study offers an applicable methodology for assessing the performance of mixed use off-grid low carbon and PV plus-energy buildings. The results aim to serve as a base for future national legal requirements for a zero carbon and PV plus-energy solar building practice especially in off-grid desert settlements in Egypt.
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| 13. |
- Das, Atanu Kumar
(författare)
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Influence of chemical additive on the physical and mechanical properties of cement-bonded composite panels made from jute stick
- 2020
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Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102. ; 31
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to observe the effects of chemical additives (calcium chloride (CaCl2) and magnesium chloride (MgCl2)) on the setting time of jute stick cement-bonded composites (CBCs). The setting time was judged based on the measured physical and mechanical properties of the composites as function of the press time. The mixing ratio of jute stick particles, cement and water was set at 2:1:1 for chemical additive (CaCl2/MgCl2) incorporated composites, and a controlled one without additive was manufactured based on jute particles and cement mixing ratio of 2:1. Three concentration levels of 6, 8 and 10% of CaCl2 and MgCl2 were used separately to produce the composite boards. In this study, the composite mixtures were cold-pressed at a pressure of 5 MPa and different pressing duration of 4, 6, 8, 12 and 16 h. Incorporation of the additives reduced the press time, and higher percentage of additives increased the physical and mechanical properties of the composite panels produced. Composite panels made with MgCl2 exhibited better performance compared with those made with CaCl2. The highest modulus of elasticity (MOE) and modulus of rupture (MOR) of the manufactured samples were 10.5 and 4595 MPa, respectively for the maximum percentage of MgCl2 addition with 6 h press time. It appears that these additives especially MgCl2 decreased the setting time of the CBCs, which can be considered as an alternative approach for the industry to produce CBCs in shorter time.
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| 14. |
- Dodoo, Ambrose, 1979-
(författare)
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Primary energy and economic implications of ventilation heat recovery for a multi-family building in a Nordic climate
- 2020
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Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102 .- 2352-7102. ; 31:101391, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- In this study the primary energy and economic implications of exhaust ventilation air heat recovery are analysed for an existing multi-family building, considering alternative air handling units (AHUs) encompassing centralised and semi-centralised units with counter-flow plate or rotary heat exchangers. The performance of the heat recovery AHUs are analysed considering different economic scenarios, frost conditions, building energy efficiency levels, energy tariffs and heat supply options including electric heat pump and district heating based on cogeneration or heat-only boiler production. Focus has been on understanding the impacts of key economic and technical parameters on the financial viability of the heat recovery AHUs, which seem lacking in current literature. The primary energy is modelled based on hourly energy balance calculations and analysis of entire natural resources chains. The economic performance is analysed considering investment costs as well as net present values of energy cost savings of the AHUs. The results show that the heat recovery AHUs are less cost-effective when using electric heat pump compared to when using district heating in the studied context. The semi-centralised AHUs with rotary heat exchanger seem slightly more cost-effective among the analysed alternatives. Frosting and defrosting need significantly influence the peak heating load and have noticeable impact on the energy and economic performance of the heat recovery AHUs. This study highlights the need for careful design and analysis of AHUs for ventilation heat recovery in buildings, for improved primary energy and cost efficiency.
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| 15. |
- Du, Linpu, et al.
(författare)
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Shaking table test on a novel mega-frame suspended structural system
- 2022
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Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 52
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Tidskriftsartikel (refereegranskat)abstract
- This paper designed a 1/20 scaled two-segment 19-story mega-frame suspended structure. The seismic behaviors of the structure equipped with viscous dampers (named damping suspended structure, DSS) or rigid connecting rods (named normal suspended structure, NSS) were studied and evaluated by a series of shaking table tests, where three seismic ground motions with two intensities were selected as input motions. Both acceleration and displacement responses of the primary and suspended structures were recorded. The results revealed that the mega-frame suspended system showed good seismic behaviors and viscous dampers could effectively improve its energy dissipation capacities. For DSS, the maximal acceleration and displacement reduction of suspended structures were 75.4% and 39.8% while those of the primary structure were 29.4% and 35.3% respectively. White noise tests showed all models were at the elastic stage under all cases. Evident relative displacements between the primary and subordinate structures were observed for DSS, in this case, the suspended floors were considered as the additional mass of the primary structure and the energy could be dissipated by the swing of suspended floors. The energy dissipation mechanism of DSS was theoretically analyzed while the effect of connection forms on vibration reduction was discussed.
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| 16. |
- Farsäter, Karin, et al.
(författare)
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Building status obtained before renovating multifamily buildings in Sweden
- 2019
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Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102.
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to analyse how energy use, building physics properties and indoor environment data have been obtained in the initial evaluation phases of multifamily building renovations in Sweden. Between 1964 and 1975, approximately one million homes were built in Sweden. These buildings are now in need of renovation. To perform proper status assessment of a building before a renovation is important both to make decisions on renovation measures on correct information as well as to be able to perform follow-ups of renovation projects. The analyses in this study was performed with questionnaires in eight case studies. Studied data included energy use, building physics properties and indoor environmental factors. The study shows that information about a building's status, and the subsequent renovation process, is often linked to one or just a few people involved in the project without any systematic documentation. When they leave their employment, due to changing jobs or retirement, documentation about the condition of the building, material choices and decision processes is often lost.
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| 17. |
- Gamil, Yaser, et al.
(författare)
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Experimental based assessment of formwork pressure theoretical design models for self-compacting concrete
- 2023
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Ingår i: Journal of Building Engineering. - : Elsevier Ltd. - 2352-7102. ; 68
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Tidskriftsartikel (refereegranskat)abstract
- Self-Compacting Concrete (SCC) offers favourable properties which help accelerate the casting time, especially in congested reinforced structures but when casting with SCC uncertainty remains a challenge on the behaviour of its formwork pressure. Researchers have introduced several design models to predict pressure and its behaviour. This research aims to assess the design models that have been reported in the literature. The assessment was carried out through a series of rigorous laboratory tests and the results from the tests served as input for the mathematical model evaluation. Twelve concrete columns with 2 m height were cast in the laboratory to study the effect of varying the input parameters in the existing design models. The formwork pressure was documented by a pressure monitoring system, with the capacity to produce instant results for real-time remote monitoring of the pressure development during and after concrete casting. The formwork pressures were calculated according to the current design models and were compared with pressure data acquitted from the laboratory tests. The results showed that the pressure predicted by the design models was typically greater than the pressure observed during the laboratory tests. The DIN18218 design model showed a relatively close approximation of the pressure distribution over the formwork height and casting time. The limitation of the models is observed when the casting rate varies, and models are sensitive to the input parameters. Thus, additional development of the current design models is needed to enable reliable estimations of the pressure, for example, in the case of low and high casting rates. The laboratory tests also showed that high casting rates and high slump flows generate higher pressures whereas higher thixotropy results in faster pressure reduction during construction.
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| 18. |
- Hagentoft, Carl-Eric, 1958, et al.
(författare)
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A conceptual model for how to design for building envelope characteristics. Impact of thermal comfort intervals and thermal mass on commercial buildings in U.S. climates
- 2021
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Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102. ; 35
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Tidskriftsartikel (refereegranskat)abstract
- The paper presents a simplified conceptual model for energy demand calculations based on building envelope characteristics, thermal mass and local climate. It is based on a network model and lumped analysis of the dynamic process. Characteristic parameters for the buildings are suggested; Driving temperature (DT), Driving temperature difference, (DTD), External Load Temperature (ELT), and Thermal Load Resistance (TLR). The Building Envelope Performance (BEP0), based on a controlled constant indoor temperature is introduced. Solution techniques using stable explicit forward differences based on analytical solutions are derived. The conceptual model has been used for mapping the Driving temperature difference and introduced two performance factors α and β. The first factor represents the effect of thermal comfort interval and thermal mass on the energy demand. The latter represents the ratio between cooling and heating energy demand. These three parameters and factors have been visualized on U.S. maps and enable a possibility to communicate the demand of energy, and cooling and the coupling to building characteristics, in a concise way.
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| 19. |
- Hassan, Osama, 1969-, et al.
(författare)
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Cross-laminated timber flooring and concrete slab flooring : A comparativestudy of structural design, economic and environmental consequences
- 2019
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Ingår i: Journal of Building Engineering. - : Elsevier. - 2352-7102. ; 26, s. 1-16
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Forskningsöversikt (refereegranskat)abstract
- This paper compares cross-laminated timber (CLT) flooring and concrete slab flooring with respect to structural design, cost analysis, and greenhouse gas emissions. The effect of floor span on design values, costs, and carbondioxide emissions is analysed in terms of structural design, economy, and environmental impact. Different crosssections are chosen for this purpose. The study shows that CLT flooring has significantly lower emissions ofclimate-impact greenhouse gases, and its ability to store carbon is significantly greater than the capacity of concrete storage. From an economic point of view, the CLT material is more expensive than concrete. However, the estimated “ready-to-assemble” cost of both floor types is quite similar. The study shows that CLT flooring can compete with a concrete slab floor when it comes to a span as wide as 7m without violating the structural requirements. However, with an increase in span, it is more difficult to meet the requirements for vibration for aCLT floor than for a concrete slab. At shorter spans, the moment capacity is often a decisive factor for concrete slabs while deformation is the decisive factor for a CLT floor. For larger spans, resonance frequency and deformation are crucial for the CLT floor, while the long-term deformation of the concrete is the decisive factor in structural design.
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| 20. |
- Hilliaho, Kimmo, et al.
(författare)
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Energy saving and indoor climate effects of an added glazed facade to a brick wall building : Case study
- 2016
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Ingår i: Journal of Building Engineering. - : Elsevier BV. - 2352-7102. ; 7, s. 246-262
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Tidskriftsartikel (refereegranskat)abstract
- This study is focused on the energy saving and indoor climate analysis of the renovation of a 1930's brick-walled building in the moderately cold climatic conditions of Malmö in southern Sweden. Three facades of the building were glassed in and the ventilation system was renewed. The purpose of this study was to investigate the effect the added glazing would have on the building's energy demand and indoor climate. Measurements were taken on site and were used as the input for computational studies performed with the help of IDA Indoor Climate and Energy software (IDA-ICE). The study showed that the heating energy demand was reduced after the glazing installation by between 5.6% and 25.3%. In addition, the mean annual temperature difference between the cavity space and the outside air was from 5.2 °C to 11.4 °C higher, depending on the design. A number of different design options were explored for the winter and also summer case-studies, as it was apparent that adding glazing decreased the level of comfort in the building's indoor environment in summer time. This problem could be solved by increasing the cavity air flow or adding new solar shading to the front or back of the glazing.
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