umu.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Efficiency factors for space heating system in buildings
Umeå University, Faculty of Science and Technology, Department of Applied Physics and Electronics. (Energy efficiency)ORCID iD: 0000-0002-2822-0000
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Umeå: Umeå University , 2018. , p. 61
Keywords [en]
Efficiency factors of space heating, hydronic panel radiator, hydronic floor heating, multilayer wall, numerical modelling, room control volume, decrement factor, time delay, heat conduction, heat convection, heat radiation, heat storage, thermal inertia, Euler solver, Newton-Raphson method, synthetic weather file, feedback and feed-forward control strategies, adaptive control, validation methodology, uncertainty bands, robustness of model predictions, thermostatic booth simulator, differential sensitivity analysis, transient model of panel radiator with multiple storage elements, active thermal mass, benchmark performance indicator, linear regression model, calibration through uncertainty bands, hybrid model of low-energy building: law driven + data driven, outdoor temperature compensation/heating curve, solar radiation model, finite difference method, heat equation
National Category
Building Technologies
Identifiers
URN: urn:nbn:se:umu:diva-151981ISBN: 978-91-7601-924-5 (print)OAI: oai:DiVA.org:umu-151981DiVA, id: diva2:1250205
Public defence
2018-10-22, N300, Naturvetarhuset, Umeå, Sweden, 13:00 (English)
Opponent
Supervisors
Available from: 2018-09-25 Created: 2018-09-21 Last updated: 2018-09-25Bibliographically approved
List of papers
1. Investigations of thermal parameters addressed to a building simulation model
Open this publication in new window or tab >>Investigations of thermal parameters addressed to a building simulation model
2015 (English)In: Proceedings of BS2015, India, Hyderabad: International Building Performance Simulation Association (IBPSA), 2015, , p. 2741-2748p. 2741-2748Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
India, Hyderabad: International Building Performance Simulation Association (IBPSA), 2015. p. 2741-2748
Keywords
Hybrid model of a room, local sensitivity analysis, HVAC, tolerance of thermal parameters
National Category
Engineering and Technology
Research subject
engineering science with specialization in microsystems technology
Identifiers
urn:nbn:se:umu:diva-116129 (URN)
Conference
Proceedings of BS2015: 14th Conference of International Building Performance Simulation Association, Hyderabad, India, Dec. 7-9, 2015.
Available from: 2016-02-08 Created: 2016-02-08 Last updated: 2018-09-21Bibliographically approved
2. Transient model of a panel radiator
Open this publication in new window or tab >>Transient model of a panel radiator
2015 (English)In: Proceedings of BS2015: 14th Conference of International Building Performance Simulation Association, Hyderabad, India, Dec. 7-9, 2015, India, Hyderabad: International Building Performance Simulation Association (IBPSA), 2015, , p. 2749-2756p. 2749-2756Conference paper, Published paper (Refereed)
Abstract [en]

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.

Place, publisher, year, edition, pages
India, Hyderabad: International Building Performance Simulation Association (IBPSA), 2015. p. 2749-2756
Keywords
Transient model of panel radiator, EN 15316
National Category
Energy Engineering
Research subject
engineering science with specialization in microsystems technology; English
Identifiers
urn:nbn:se:umu:diva-116130 (URN)
Conference
Proceedings of BS2015: 14th Conference of International Building Performance Simulation Association, Hyderabad, India, Dec. 7-9, 2015.
Available from: 2016-02-08 Created: 2016-02-08 Last updated: 2018-09-21Bibliographically approved
3. Predictions' robustness of one-dimensional model of hydronic floor heating: novel validation methodology using a thermostatic booth simulator and uncertainty analysis
Open this publication in new window or tab >>Predictions' robustness of one-dimensional model of hydronic floor heating: novel validation methodology using a thermostatic booth simulator and uncertainty analysis
2018 (English)In: Journal of Building Physics, ISSN 1744-2591, E-ISSN 1744-2583, Vol. 41, no 5, p. 418-444Article in journal, Editorial material (Refereed) Published
Abstract [en]

Hydronic floor heating models provide predictions in estimating heat transfer rates and floor surface temperature. Information on the model performance and range of validity of its results are often lacking in literature. Researchers have to know the accuracy and robustness of the model outcomes for performing energy and climate comfort calculations. This article proposes a novel validation methodology based on the uncertainty analysis of input data/parameters of one-dimensional model of hydronic floor heating tested in a thermostatic booth simulator and compared with experimental measurements. The main results are: (1) prediction accuracy between 0.4% and 2.9% for Tf and between 0.7% and 7.8% for qup when the serpentine has tube spacing (p) of 0.30 m, (2) prediction accuracy between 0.5% and 1.4% for Tf and between 8.7% and 12.9% for qup with p = 0.15m and (3) Tfld mostly affects predictions with oscillations between 6.2% and 2.2% for qup. This model provides robust and reliable predictions exclusively for qup when p = 0.30m.

Place, publisher, year, edition, pages
Sage Publications, 2018
Keywords
One-Dimensional model of hydronic floor heating, thermostatic booth simulator, validation methodology, uncertainty bands, differential sensitivity analysis, robustness of model's predictions
National Category
Building Technologies
Research subject
Physics
Identifiers
urn:nbn:se:umu:diva-136486 (URN)10.1177/1744259117721002 (DOI)000429862600002 ()
Available from: 2017-06-19 Created: 2017-06-19 Last updated: 2018-09-21Bibliographically approved
4. Practical support for evaluating efficiency factors of a space heating system in cold climates: modelling and simulation of hydronic panel radiator with different location of connection pipes
Open this publication in new window or tab >>Practical support for evaluating efficiency factors of a space heating system in cold climates: modelling and simulation of hydronic panel radiator with different location of connection pipes
2017 (English)In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 10, no 5, p. 1253-1267Article in journal (Refereed) Published
Abstract [en]

Plenty of technical norms, included in the EPBD umbrella, assess the performance of buildings or its sub-systems in terms of efficiency. In particular, EN 15316 and its sub-sections, determine the system energy requirements and the system efficiencies of space heating system. This paper focuses on the estimation of efficiencies for emission of hydronic radiators. The assessment of efficiencies for emission occurs by evaluating the amount of heat emitted  from the heat emitter and the extra thermal losses towards building envelope. The heat emitted from radiators varies during the heating up/cooling down phases. A factor that influences the heat emitted during these phases is the location of connection pipes of the radiator. Connection pipes can be located on opposite side or at the same side of the radiator. To better estimate the heat emitted from radiators a transient model with multiple storage elements is used in a building simulation model. Sensitivity analysis encompasses all  the possible variations on extra thermal losses due to the building location in different climates, the heaviness of active thermal mass and the type of radiator local control. The final outcome of this paper is a practical support where the designer can easily assess the efficiencies for emission of hydronic radiators  for Swedish buildings. As main result, (i) the efficiency for control of space heating system is higher in Northern climates than in Southern climates, (ii) heavy active thermal masses allow higher efficiencies for emission than light active thermal masses, (iii) connection pipes located on the same side of the radiator enable higher efficiencies for emission than pipes located on opposite side.

Keywords
Hydronic panel radiator, Efficiency factors, Connection pipes, Transient model with multiple storage elements, Climate, Active thermal mass
National Category
Building Technologies
Research subject
Systems Analysis
Identifiers
urn:nbn:se:umu:diva-121199 (URN)10.1007/s12053-017-9506-7 (DOI)000411865800013 ()
Available from: 2016-05-29 Created: 2016-05-29 Last updated: 2018-09-25Bibliographically approved
5. Paradoxes in understanding the Efficiency Factors of Space Heating
Open this publication in new window or tab >>Paradoxes in understanding the Efficiency Factors of Space Heating
2019 (English)In: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 12, no 3, p. 777-786Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Springer, 2019
Keywords
Efficiency factors, Space heating, Accuracy 1D model of hydronic floor heating, Outdoor climate, Performance indicator, Solar radiation, Benchmark, Linear regression model
National Category
Building Technologies
Research subject
engineering science with specialization in microsystems technology
Identifiers
urn:nbn:se:umu:diva-149931 (URN)10.1007/s12053-018-9692-y (DOI)000461106400015 ()2-s2.0-85049553312 (Scopus ID)
Projects
Reliability and robustness of efficiency factors theory of the space heating equipped with hydronic technologies
Available from: 2018-06-29 Created: 2018-06-29 Last updated: 2019-04-04Bibliographically approved
6. The impact of control strategies on space heating system efficiency in low-energy buildings
Open this publication in new window or tab >>The impact of control strategies on space heating system efficiency in low-energy buildings
Show others...
2019 (English)In: Building Services Engineering Research & Technology, ISSN 0143-6244, E-ISSN 1477-0849, Vol. 40, no 6, p. 714-731Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
London: Sage Publications, 2019
Keywords
Efficiency factors of space heating and distribution system, Calibration through uncertainty bands, Hybrid model of low-energy building: law-driven + data-driven model, Outdoor temperature compensation or heating curve, Feedback and feed-forward control loop + adaptive control, Solar radiation model
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-151980 (URN)10.1177/0143624418822454 (DOI)000491440700005 ()2-s2.0-85060767454 (Scopus ID)
Available from: 2018-09-21 Created: 2018-09-21 Last updated: 2019-12-19Bibliographically approved
7. One dimensional model of transient heat conduction through multilayer walls/slabs: The functionality of insulation and brick materials in terms of decrement factor and time lag
Open this publication in new window or tab >>One dimensional model of transient heat conduction through multilayer walls/slabs: The functionality of insulation and brick materials in terms of decrement factor and time lag
2016 (English)Manuscript (preprint) (Other academic)
Abstract [en]

Multilayer wall is a common type of building envelope used in buildings located in cold climates. The building envelope is typically composed by internal and external masses made by bricks or concrete separated by a large thickness of insulation material. This paper investigates the thermal behavior of a multilayer wall subjected to temperature excitation on both wall sides. The analysis is conducted by discretizing the continuous space and time variables of the mathematical model identified in the heat equation. Euler backwards solves the numerical model of multilayer wall by providing an unconditionally stable solution. The step response test shows the correct working of the model which reaches the steady state solution. The results of this paper are expressed in terms of temperature of each wall layer against the time. In particular, (i) the large thickness of insulation material separates thermodynamically the outside external mass from the internal mass, (ii) 20 cm thickness of insulation material damps the heat wave with a decrement factor of 3.41 °ͦC and a time lag of 1 hour, (iii) the external brick layer damps the heat wave with a decrement factor of 1.97 °ͦC and a time lag of 5 hours.

Keywords
Heat equation, Euler Implicit solver, Multilayer walls/slabs, Finite Dierence Method
National Category
Building Technologies
Research subject
Systems Analysis; engineering science with specialization in microsystems technology
Identifiers
urn:nbn:se:umu:diva-121200 (URN)
Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2018-09-25

Open Access in DiVA

fulltext(4435 kB)142 downloads
File information
File name FULLTEXT01.pdfFile size 4435 kBChecksum SHA-512
3adb2947f1708ee53fcc46820b57c8ffc0052ff93baf8f243ff7219cb664d3dae3d8046bd5187681089fba183cdb1a6c32eb0df3581ff30149c83f1b11565f2e
Type fulltextMimetype application/pdf
spikblad(203 kB)19 downloads
File information
File name SPIKBLAD01.pdfFile size 203 kBChecksum SHA-512
10c2d780c493db4bf6a9210ec10322d00fcc8ccc4df0946b171236447731f1e9d675226d5134240ea3546c07f913d6ed55e0ebd89ea0c2fc45db8366cd945d1a
Type spikbladMimetype application/pdf

Authority records BETA

Brembilla, Christian

Search in DiVA

By author/editor
Brembilla, Christian
By organisation
Department of Applied Physics and Electronics
Building Technologies

Search outside of DiVA

GoogleGoogle Scholar
Total: 142 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 1029 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf