| 1. |
- Brembilla, Christian, 1983-
(författare)
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Efficiency factors for space heating system in buildings
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis focuses on the efficiency of the space heating system. In particular, the efficiency factors measure the efficiency of thermal zone. The efficiency factors measures how the energy is used in a space heating. Efficiency factors relatively close to one mean that the energy is used "efficiently'', by contrast, efficiency factors close to the zero mean that the majority of the energy is lost to the outdoor environment. This method for the appraisal of space heating performance reads as if it is apparently simple and intuitive. In reality, the efficiency factor method has several pitfalls.The thesis provides tools, insights and remarks on how to apply the efficiency factor method to space heating systems equipped with hydronic panel radiator and floor heating respectively. Models of the latter heaters together with the multilayer wall were developed and validated to understand the reliability of their predictions. The hypothesis is that the heat stored in the building thermal mass and heaters plays a role in defining the building thermal performance and as a result in the appraisal of the efficiency factors. The validation is based on the sensitivity bands of the models' predictions. The heaters were tested in in a thermostatic booth simulator. Benefits and drawbacks of each model were highlighted to increase awareness of their use in the engineering fields. The results showed how the models accounting for the heat stored performed the charging phase. In addition, results of how the multilayer wall delayed and damped down the heat wave coming from the outdoor environment were presented with the appraisal of the decrement factor and time delay of the indoor temperature. The results of the efficiency factors analysis reveal how the weather affects the efficiency of each locality situated in cold climates. Lastly how different control strategies impact on the efficiency factors of space heating and its distribution system. To conclude, this study highlights the paradoxes around the efficiency factor method. The thesis proposes how such factors have to be interpreted by researchers and scientists tackling the lack of information around this topic.
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| 2. |
- Brembilla, Christian, 1983-, et al.
(författare)
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Hybrid heating system for open-space office/laboratory
- 2015
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Ingår i: Energy, Science and Technology 2015. - Karlsruher, Germany : Karlsruhe, KIT. ; , s. 315-315
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Konferensbidrag (refereegranskat)abstract
- Open-space office/laboratory are quite common in Scandinavia and they are usually designed for multipurposework. There are office area where is possible to work standing up and in the same time to work at the desk. Forthis purpose a hybrid heating system made by electric convectors and panel radiators is investigated. Two stepresponse tests of the hybrid heating system are performed at the laboratory of Umeå University. The first test isexecuted during the week, disturbances from heat sources degrading the quality of the results. The second test isperformed during week-end. The error analysis shows a maximum discrepancies of +0.6 °C between measuredand simulated data. However, a thermal time constant of the room can be deducted and use it for controlling purposes.
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| 3. |
- Brembilla, Christian, 1983-, et al.
(författare)
-
Hybrid heating system for open-space office/laboratory
- 2015
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Ingår i: Energy, Science and Technology 2015. - Karlsruhe : Karlsruher Institut für Technologie (KIT). ; , s. 315-315
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Konferensbidrag (refereegranskat)abstract
- Open-space office/laboratory are quite common in Scandinavia and they are usually designed for multipurpose work. There are office area where is possible to work standing up and in the same time to work at the desk. For this purpose a hybrid heating system made by electric convectors and panel radiators is investigated. Two step response tests of the hybrid heating system are performed at the laboratory of Umeå University. The first test is executed during the week, disturbances from heat sources degrading the quality of the results. The second test is performed during week-end. The error analysis shows a maximum discrepancies of +0.6 °C between measured and simulated data. However, a thermal time constant of the room can be deducted and use it for controlling purposes.
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| 4. |
- Brembilla, Christian, 1983-, et al.
(författare)
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Investigation of thermal parameters addressed to a building simulation model
- 2015
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Ingår i: Energy, Science and Technology 2015. - Karlsruher, Germany : Karlsruher Institute of Technology (KIT). ; , s. 128-
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Konferensbidrag (refereegranskat)abstract
- Introduction The uncertainty of setting input parameters in a building model can have a major impact on the simulated output. The tolerance of thermal parameters is a necessary information that helps modeler to know the influence of eachfactors on the outcomes. This paper shows the allowable tolerance of thermal parameters in order to build anaccurate building model.
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| 5. |
- Brembilla, Christian, 1983-, et al.
(författare)
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Investigations of thermal parameters addressed to a building simulation model
- 2015
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Ingår i: Proceedings of BS2015. - India, Hyderabad : International Building Performance Simulation Association (IBPSA). ; , s. 2741-2748, s. 2741-2748
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Konferensbidrag (refereegranskat)abstract
- This paper shows the tolerance of thermal parameters addressed to a building simulation model in relation to the local control of the HVAC system. This work is suitable for a modeler that has to set up a building simulation model. The modeler has to know which parameter needs to be considered carefully and vice-versa which does not need deep investigations. Local differential sensitivity analysis of thermal parameters generates the uncertainty bands for the indoor air. The latter operation is repeated with P, PI and PID local control of the heating system. In conclusion, the local control of a room has a deterministic impact on the tolerance of thermal parameters.
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| 6. |
- Brembilla, Christian, 1983-, et al.
(författare)
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Paradoxes in understanding the Efficiency Factors of Space Heating
- 2019
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Ingår i: Energy Efficiency. - Dordrecht : Springer. - 1570-646X .- 1570-6478. ; 12:3, s. 777-786
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Tidskriftsartikel (refereegranskat)abstract
- Efficiency factors are here defined as the thermal energy performance indicators of the space heating. Until recently, the efficiency factors were assumed as one value for space heating located in any climate. This study addresses the problem of how the outdoor climate affects the efficiency factors of a space heating equipped with 1D model of hydronic floor heating. The findings show how the efficiency factors, computed with two numerical methods, are correlated with the solar radiation. This study highlights the paradoxes in understanding the results of efficiency factors analysis. This work suggests how to interpret and use the efficiency factors as a benchmark performance indicator.
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| 7. |
- Brembilla, Christian, 1983-, et al.
(författare)
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The impact of control strategies on space heating system efficiency in low-energy buildings
- 2019
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Ingår i: Building Services Engineering Research & Technology. - London : Sage Publications. - 0143-6244 .- 1477-0849. ; 40:6, s. 714-731
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Tidskriftsartikel (refereegranskat)abstract
- In this study efficiency factors measures the thermal energy performance for space heating. This study deals with the influence of control strategies on the effriciency factors of space heating and its distribution system. An adaptive control is developed and applied to two types of heating curves (linear and non-linear) for a low-energy building equipped with renewable energy sources. The building is modelled with a hybrid approach (law driven + data driven model). The design of the floor heating is calibrated and validated by assessing the uncertainty bands for low temperatures and mass flow rate. advantages and disavantages of linear and non-linear heating curves are highlighted to illustrate their impact on space heating thermodynamic behaviour and on the efficiency factors of the space heating system.Practical application: The study reveals that applying commercial building energy simulation software is worthwhile to determine reliable performance predictions. Oversimplified building models, in particular when considering building thermal mass, are not capable of simulating the thermodynamic response of a building subjected to different control strategies. The application of different heating cuirves (linear and non-linear) to massless building models leaves the amount of mass flow rate delivered to the space heating unchanged when the building is subjected to sharp variations of the outdoor temperature.
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| 8. |
- Brembilla, Christian, 1983-, et al.
(författare)
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Transient model of a panel radiator
- 2015
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Ingår i: Energy, Science and Technology 2015. - Karlsruher, Germany : Karlsruher Institut für Technologie (KIT). ; , s. 321-321, s. 321-321
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Konferensbidrag (refereegranskat)abstract
- This paper shows a detailed transient model of a panel radiator considered as a system of multiple storageelements. The experiment records the temperature surface of the panel in the process of heating up. Thequalitative results of the experiment suggest the more appropriate technique for modelling this technology. The transient model performs the modelling with horizontal thermal capacitances connected in series. This modelcalculates the temperature of exhaust flow, heat emission towards indoor environment, temperature gradient onpanel surface, dead and balancing time identified numerically on the chart.
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| 9. |
- Brembilla, Christian, 1983-, et al.
(författare)
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Transient model of a panel radiator
- 2015
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Ingår i: Proceedings of BS2015. - India, Hyderabad : International Building Performance Simulation Association (IBPSA). ; , s. 2749-2756
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Konferensbidrag (refereegranskat)abstract
- This paper shows a transient model of a hydronic panel radiator modelled as a system of multiple storage elements. The experiment´s results suggest the more suitable technique for modelling this technology. The panel radiator is modelled numerically with eight thermal capacitance connected in series by keeping a memory of the heat injected in the thermal unit. The comparison of the performance among lumped steadystate models and transient model, in terms of heat emission and temperature of exhaust flow, shows the potential of the latter approach. To conclude, (1) the transient phase is essential for modelling stocky panels, and (2) this type of modelling has to be addressed for evaluating the performance of low energy buildings.
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