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Bales, Chris
Publications (10 of 35) Show all publications
Wang, X., Xia, L., Bales, C., Zhang, X., Copertaro, B., Pan, S. & Wu, J. (2020). A systematic review of recent air source heat pump (ASHP) systems assisted by solar thermal, photovoltaic and photovoltaic/thermal sources. Renewable energy, 146, 2472-2487
Open this publication in new window or tab >>A systematic review of recent air source heat pump (ASHP) systems assisted by solar thermal, photovoltaic and photovoltaic/thermal sources
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2020 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 146, p. 2472-2487Article in journal (Refereed) Published
National Category
Energy Engineering
Research subject
Energy and Built Environments
Identifiers
urn:nbn:se:du-30632 (URN)10.1016/j.renene.2019.08.096 (DOI)2-s2.0-85071196687 (Scopus ID)
Available from: 2019-08-23 Created: 2019-08-23 Last updated: 2019-09-17Bibliographically approved
Menegon, D., Persson, T., Haberl, R., Bales, C. & Haller, M. (2020). Direct characterisation of the annual performance of solar thermal and heat pump systems using a six-day whole system test. Renewable energy, 146, 1337-1353
Open this publication in new window or tab >>Direct characterisation of the annual performance of solar thermal and heat pump systems using a six-day whole system test
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2020 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 146, p. 1337-1353Article in journal (Refereed) Published
National Category
Energy Systems
Research subject
Energy and Built Environments
Identifiers
urn:nbn:se:du-30590 (URN)10.1016/j.renene.2019.07.031 (DOI)2-s2.0-85068958809 (Scopus ID)
Available from: 2019-08-06 Created: 2019-08-06 Last updated: 2019-08-06Bibliographically approved
Dermentzis, G., Ochs, F., Gustafsson, M., Calabrese, T., Siegele, D., Feist, W., . . . Bales, C. (2019). A comprehensive evaluation of a monthly-based energy auditing tool through dynamic simulations, and monitoring in a renovation case study. Energy and Buildings, 183, 713-726
Open this publication in new window or tab >>A comprehensive evaluation of a monthly-based energy auditing tool through dynamic simulations, and monitoring in a renovation case study
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2019 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 183, p. 713-726Article in journal (Refereed) Published
Abstract [en]

An energy auditing tool (PHPP) was evaluated against a dynamic simulation tool (TRNSYS) and used for the assessment of energy conservation measures in a demo case study. The comprehensive comparison of useful heating and cooling demands and loads included three building types (single-, multi-family house, and office), three building energy levels (before renovation and after renovation with a heating demand of 45 and 25 kWh/(m²·a)) and seven European climates. Dynamic simulation results proved PHPP (monthly energy balance) to be able to calculate heating demand and energy savings with good precision and cooling demand with acceptable precision compared to detailed numerical models (TRNSYS). The average deviation between the tools was 8% for heating and 15% for cooling (considering climates with a relevant cooling load only). The higher the thermal envelope quality was, i.e. in case of good energy standards and in cold climates, the better was the agreement. Furthermore, it was confirmed that PHPP slightly overestimates the heating and cooling loads by intention for system design. The renovation design of a real multi-family house was executed using PHPP as energy auditing tool. Several calculation stages were performed for (a) baseline, (b) design phase, and (c) verification with monitoring in order to calculate the corresponding heating demand. The PHPP model was calibrated twice, before and after the renovation. The necessity for tool calibration, especially for the baseline, was highlighted increasing the confidence with respect to a number of boundary conditions. In this study, PHPP was tested as an energy auditing tool aiming to be a versatile and less error-prone alternative to more complex simulation tools, which require much more expert knowledge and training. 

Keywords
Building simulation, Energy audit, Energy conservation, PHPP, Renovation, TRNSYS
National Category
Energy Engineering
Research subject
Energy, Forests and Built Environments
Identifiers
urn:nbn:se:du-29096 (URN)10.1016/j.enbuild.2018.11.046 (DOI)000456760000053 ()2-s2.0-85057811004 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 314461
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-02-14Bibliographically approved
Dipasquale, C., Fedrizzi, R., Bellini, A., Gustafsson, M., Ochs, F. & Bales, C. (2019). Database of energy, environmental and economic indicators of renovation packages for European residential buildings. Energy and Buildings, 203, Article ID 109427.
Open this publication in new window or tab >>Database of energy, environmental and economic indicators of renovation packages for European residential buildings
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2019 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 203, article id 109427Article in journal (Refereed) Published
Abstract [en]

Increasing the energy efficiency with a vast impact in the residential building stock requires retrofit solutions that can be exploited with respect to a wide range of different building typologies and climates. Several tools and methodologies are nowadays available both for the assessment of building demands and for the individuation of optimum retrofit solutions. However, they are usually either too complex to be adopted by professionals or, on the contrary, oversimplified to account for the full complexity of a deep envelope and HVAC system retrofit. In this context, this paper describes a methodology developed to generate reliable information on retrofit solutions for typical buildings in different climatic conditions. Detailed numerical models are used to simulate a number of combinations of envelope and HVAC systems retrofit measures and renewable energy integration. Energy performance results are gathered in a database that allows comparing solutions, spanning over a range of more than 250,000 combinations of building types, age of construction, climates, envelope performance levels and HVAC systems configurations. Economic feasibility is also derived for each of the combinations. In this way, the accurateness of a detailed and validated calculation is made available to assist during the decision making process, with minimum computational effort being required by professionals: the variety and density of evaluated combinations allows to easily assess the performance of a specific case by interpolating among instances previously assessed. The applicability of the results to different climates and similar building typologies is verified by a comparison of the database results with a specific case dynamic simulation.

Keywords
Building retrofit, Economic analysis, Simulation-based database, Residential building stock
National Category
Energy Engineering
Research subject
Energy and Built Environments, iNSPiRE
Identifiers
urn:nbn:se:du-30743 (URN)10.1016/j.enbuild.2019.109427 (DOI)2-s2.0-85072563912 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 314461
Available from: 2019-09-24 Created: 2019-09-24 Last updated: 2019-09-30Bibliographically approved
Persson, T., Wiertzema, H., Win, K. M. & Bales, C. (2019). Modelling of dynamics and stratification effects in pellet boilers. Renewable energy, 134, 769-782
Open this publication in new window or tab >>Modelling of dynamics and stratification effects in pellet boilers
2019 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 134, p. 769-782Article in journal (Refereed) Published
Abstract [en]

Optimizing solar and pellet heating systems can be performed by system simulations in TRNSYS. However; this requires detailed boiler models that can properly model the thermal behaviour of the boilers, such as stratification and thermal response. This study uses a combination of existing models for modelling of the pellet burner part (TRNSYS Type 210) and the water volume (TRNSYS Type 340). This approach addresses the thermal dynamics and internal stratification more accurately than other available models. The objectives of this work are to develop a method for parameter identification for the model and to validate this method and the model itself. Sets of parameters are identified for two pellet boilers and one pellet stove with a water jacket (extended room heater) and the model is validated with a realistic dynamic operation sequence. The results show that modelling of stratification is essential in order to model the true behaviour of residential boilers. The test sequences used were adequate to parameterise the models and to provide the desired accuracy, except regarding the heat losses to room air. The model shows good accuracy for a stove and one boiler, but slightly worse performance for the other boiler regarding dynamics and modelling of the stratification.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
System simulation; Modelling; Validation; Pellet boiler; Pellet stove
National Category
Energy Engineering
Research subject
Energy, Forests and Built Environments, SWX-Energi, Integrerade system för sol och biobränsle
Identifiers
urn:nbn:se:du-28900 (URN)10.1016/j.renene.2018.11.052 (DOI)000456760900067 ()2-s2.0-85057272860 (Scopus ID)
Available from: 2018-11-14 Created: 2018-11-14 Last updated: 2019-02-14Bibliographically approved
Psimopoulos, E., Bee, E., Widén, J. & Bales, C. (2019). Techno-economic analysis of control algorithms for an exhaust air heat pump system for detached houses coupled to a photovoltaic system. Applied Energy, 249, 355-367
Open this publication in new window or tab >>Techno-economic analysis of control algorithms for an exhaust air heat pump system for detached houses coupled to a photovoltaic system
2019 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 249, p. 355-367Article in journal (Refereed) Published
Abstract [en]

Operational control strategies for the heating system and “smart” utilization of energy storage were developed and analyzed in a simulation based case study of a single-family house with exhaust air heat pump and photovoltaic system. Rule based control algorithms that can easily be implemented into modern heat pump controllers were developed with the aim to minimize final energy and maximize self-consumption by the use of the thermal storage of the building, the hot water tank and electrical storage. Short-term weather and electricity price forecasts are used in some of the algorithms. Heat supply from an exhaust air heat pump is limited by the ventilation flow rate fixed by building codes, and compact systems employ an electric heater as backup for both space heating and hot water. This heater plays an important role in the energy balance of the system. A typical system designed for new detached houses in Sweden was chosen for the study. This system, together with an independent photovoltaic system, was used as a base case and all results are compared to those for this base case system. TRNSYS 17 was used to model the building and system as well as the control algorithms, and special care was taken to model the use of the backup electric heater as this impacts significantly on final energy use. Results show that the developed algorithms can reduce final energy by 5–31% and the annual net cost for the end user by 3–26%, with the larger values being for systems with a battery storage. Moreover, the annual use of the backup electric heater can be decreased by 13–30% using the carefully designed algorithms.

Keywords
Photovoltaics, Heat pump, Forecast services, Thermal storage, Electrical storage, Control algorithms
National Category
Energy Systems
Research subject
Energy and Built Environments
Identifiers
urn:nbn:se:du-30003 (URN)10.1016/j.apenergy.2019.04.080 (DOI)000472692200029 ()2-s2.0-85065118179 (Scopus ID)
Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-07-22Bibliographically approved
Huang, P., Lovati, M., Zhang, X., Bales, C., Hallbeck, S., Becker, A., . . . Maturi, L. (2019). Transforming a residential building cluster into electricity prosumers in Sweden: Optimal design of a coupled PV-heat pump-thermal storage-electric vehicle system. Applied Energy, 255, Article ID 113864.
Open this publication in new window or tab >>Transforming a residential building cluster into electricity prosumers in Sweden: Optimal design of a coupled PV-heat pump-thermal storage-electric vehicle system
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2019 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 255, article id 113864Article in journal (Refereed) Published
Abstract [en]

Smart grid is triggering the transformation of traditional electricity consumers into electricity prosumers. This paper reports a case study of transforming an existing residential cluster in Sweden into electricity prosumers. The main energy concepts include (1) click-and-go photovoltaics (PV) panels for building integration, (2) centralized exhaust air heat pump, (3) thermal energy storage for storing excess PV electricity by using heat pump, and (4) PV electricity sharing within the building cluster for thermal/electrical demand (including electric vehicles load) on a direct-current micro grid. For the coupled PV-heat pump-thermal storage-electric vehicle system, a fitness function based on genetic algorithm is established to optimize the capacity and positions of PV modules at cluster level, with the purpose of maximizing the self-consumed electricity under a non-negative net present value during the economic lifetime. Different techno-economic key performance indicators, including the optimal PV capacity, self-sufficiency, self-consumption and levelized cost of electricity, are analysed under impacts of thermal storage integration, electric vehicle penetration and electricity sharing possibility. Results indicate that the coupled system can effectively improve the district-level PV electricity self-consumption rate to about 77% in the baseline case. The research results reveal how electric vehicle penetrations, thermal storage, and energy sharing affect PV system sizing/positions and the performance indicators, and thus help promote the PV deployment. This study also demonstrates the feasibility for transferring the existing Swedish building clusters into smart electricity prosumers with higher self-consumption and energy efficiency and more intelligence, which benefits achieving the ‘32% share of renewable energy source’ target in EU by 2030.

Keywords
Building cluster, Prosumer, PV optimization, Heat pump, Thermal storage, Electrical vehicle
National Category
Energy Engineering
Research subject
Energy and Built Environments, Energy Matching
Identifiers
urn:nbn:se:du-30679 (URN)10.1016/j.apenergy.2019.113864 (DOI)2-s2.0-85071963501 (Scopus ID)
Funder
EU, Horizon 2020, 768766
Available from: 2019-09-10 Created: 2019-09-10 Last updated: 2019-10-01Bibliographically approved
Fiedler, F., Bales, C., Persson, J., Gustavsson, M., Kovacs, P., Hemlin, O., . . . Larsson, D. (2018). Miljontak Delprojekt 2: Sammanfattning av litteratursammanställning.
Open this publication in new window or tab >>Miljontak Delprojekt 2: Sammanfattning av litteratursammanställning
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2018 (Swedish)Report (Other academic)
Publisher
p. 11
National Category
Building Technologies
Research subject
Energy, Forests and Built Environments, EMC Energi- och miljökompetenscentrum i Dalarna
Identifiers
urn:nbn:se:du-27765 (URN)
Projects
Miljontak
Funder
Swedish Energy Agency, 41857-1
Available from: 2018-06-05 Created: 2018-06-05 Last updated: 2018-06-07Bibliographically approved
Poppi, S., Sommerfeldt, N., Bales, C., Madani, H. & Lundqvist, P. (2018). Techno-economic review of solar heat pump systems for residential heating applications. Renewable & sustainable energy reviews, 81, 22-32
Open this publication in new window or tab >>Techno-economic review of solar heat pump systems for residential heating applications
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2018 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 81, p. 22-32Article in journal (Refereed) Published
Abstract [en]

Solar heat pump systems (SHPs) have been investigated for several decades and have been proven to increase the share of renewable energy and reduce electric energy demand in residential heating applications. Many review articles have been published on the subject, however literature discussing the techno-economics of different solar technologies (thermal, photovoltaic and hybrid thermal/photovoltaic) in combination with heat pumps is lacking, and thus to directly compare the merits of different SHPs is not an easy task. The objectives of this study are: a) review the different system boundaries and the main performance indicators used for assessing energetic and economic performances; b) review techno-economic studies in the literature and identify which studies give enough information and are compatible enough for making an economic inter-comparison; c) present an economic inter-comparison based on the identified systems. The results show that there is a lack of studies including an economic assessment of solar photovoltaic and heat pump systems. Additionally, there are no consistent boundaries or approaches to the study structures, making comparisons between systems difficult. In conclusion, a standardized or broadly accepted definition of technical and economic performance for SHPs is needed. Despite this, the study has shown that there are clear trends for decreasing payback times for SHPs, both solar thermal (ST) and photovoltaic (PV), with decreasing heating degree-days and with increasing solar resource.

Keywords
Performance indicators, Solar heat pump systems, System boundary, System configuration
National Category
Energy Engineering
Research subject
Energy, Forests and Built Environments
Identifiers
urn:nbn:se:du-25649 (URN)10.1016/j.rser.2017.07.041 (DOI)000417070500002 ()2-s2.0-85024839540 (Scopus ID)
Available from: 2017-07-31 Created: 2017-07-31 Last updated: 2018-03-26Bibliographically approved
Gustafsson, M., Dipasquale, C., Poppi, S., Bellini, A., Fedrizzi, R., Bales, C., . . . Holmberg, S. (2017). Economic and environmental analysis of energy renovation packages for European office buildings. Energy and Buildings, 148, 155-165
Open this publication in new window or tab >>Economic and environmental analysis of energy renovation packages for European office buildings
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2017 (English)In: Energy and Buildings, ISSN 0378-7788, E-ISSN 1872-6178, Vol. 148, p. 155-165Article in journal (Refereed) Published
Abstract [en]

A large share of the buildings in Europe are old and in need of renovation, both in terms of functional repairs and energy efficiency. While many studies have addressed energy renovation of buildings, they rarely combine economic and environmental life cycle analyses, particularly for office buildings. The present paper investigates the economic feasibility and environmental impact of energy renovation packages for European office buildings. The renovation packages, including windows, envelope insulation, heating, cooling and ventilation systems and solar photovoltaics (PV), were evaluated in terms of life cycle cost (LCC) and life cycle assessment (LCA) through dynamic simulation for different European climates. Compared to a purely functional renovation, the studied renovation packages resulted in up to 77% lower energy costs, 19% lower total annualized costs, 79% lower climate change impact, 89% lower non-renewable energy use, 66% lower particulate matter formation and 76% lower freshwater eutrophication impact over a period of 30 years. The lowest total costs and environmental impact, in all of the studied climates, were seen for the buildings with the lowest heating demand. Solar PV panels covering part of the electricity demand could further reduce the environmental impact and, at least in southern Europe, even reduce the total costs. © 2017 Elsevier B.V.

Keywords
Energy renovation, LCA, LCC, Office buildings, TRNSYS
National Category
Energy Engineering
Research subject
Energy, Forests and Built Environments
Identifiers
urn:nbn:se:du-25094 (URN)10.1016/j.enbuild.2017.04.079 (DOI)000404705000013 ()2-s2.0-85019454202 (Scopus ID)
Available from: 2017-06-05 Created: 2017-06-05 Last updated: 2017-11-06Bibliographically approved
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