Conference Agenda

Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).

Please note that all times are shown in the time zone of the conference. The current conference time is: 29th July 2021, 05:23:17am CEST

Session Overview
Session 2: HVAC system solutions
Tuesday, 22/June/2021:
1:00pm - 2:30pm

Session Chair: Alireza Afshari
Session Co-chair: Johan Mattsson
Location: Zoom room #1
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1:00pm - 1:05pm

Operation status and improvements of integrated hybrid VRF system

Yusuke Tosaka1, Shota Hagi1, Tokimi Kawase2, Tatsuo Nobe1

1Kogakuin University, Japan; 2Yasui Architects&Engineers,Inc.

In recent years, the importance of energy saving and the best mix of energy has increased.

In particular, the best mix of energy is important in terms of energy supply stability. There is a need for air conditioning with energy options. Therefore, an integrated hybrid variable refrigerant flow system (Hybrid VRF system) was developed in which gas engine driven heat pump (GHP) and electric heat pump (EHP) were connected to the same refrigerant system. The Hybrid VRF system is a type of packaged air conditioner. This system can freely change the ratio of EHP and GHP. By controlling the operating ratio of EHP and GHP, Hybrid VRF system achieve high operating efficiency. It operates EHP when the load factor is low, and operates GHP when the load factor is medium. When the load factor becomes high, booth EHP and GHP are operated. Packaged air conditioners are often used in small to medium-sized buildings. However, the actual performance characteristics of Hybrid VRF system have not been investigated. In this report, the authors conducted an actual survey of Hybrid VRF system which was introduced to a commercial facility. As a result of actual survey, it was found that the actual operation was different from the expected operation. It turned out that GHP is often operated when the load factor of the system is low. This operation is not optimal operation Therefore, the authors calculated the energy consumption when the system is operated in optimal operation. From the data obtained from the actual survey, we created the characteristic formulas of the primary COP and the load factor. Next, we created a table that defines the optimum operating ratios of GHP and EHP for each load factor. We calculated the primary energy consumption in optimum operation from the load factor and the amount of heat produced and the characteristic formula obtained in the actual measurement. Compared with the energy consumption of actual driving, the energy consumption of optimal driving is smaller. In optimal operation, primary energy consumption was about 25% less than the actual energy consumption. It was found that Hybrid VRF system which was actually measured this time has points to be improved in the operation method.

1:05pm - 1:17pm

Evaluation of a novel 3-pipe solution for hydronic heat distribution in passive-house standard apartment buildings

Jonathan Lundblad, Nora Ingrid Andreassen, Johanna Olsen, Arnab Chaudhuri

Department of Civil Engineering and Energy Technology, OsloMet, Norway

The energy efficiency of new buildings in Norway has been steadily improved over the last decades, but with less heating, hydronic heating systems have adversely increased in price. Lessening electric power consumption in new buildings is an important part of the government’s plan to de-carbonize, in which hydronic heating is a suitable alternative for electric heating. In this regard, a developer claimed to have found a potential cost-efficient hydronic solution in terms of investment cost. This solution is based on two measures, using the Domestic Hot Water (DHW) circulation loop to cover both DHW demand as well as space heating demand in the building, and significantly reducing the number of heat emitters. In this work, we studied the possible benefits and the issues associated with this solution and performed an analysis based on the following accounts, i) the distribution system, ii) indoor climate, iii) energy demand/consumption, iv) hygienic security. A newly finished apartment complex located in central Oslo is chosen for this purpose. Two apartments and the central heating are examined by inspection, experimental measurements, and Computational Fluid Dynamics (CFD) simulations. The distribution system is examined to confirm the alleged cost efficiency with a simplified cost calculation based on the BIM-model and the documentation provided by the developers. We estimated an additional cost of 67 NOK per square meter in comparison to the electrical heating. The end user could also financially benefit from using less expensive district heating. Using fan-coils as main heat emitter in each apartment was found to produce satisfactory indoor climate, however, in one apartment it was found that poor planning sabotaged its intended function which negatively affected indoor climate. Additionally, we found a lack of measures to protect the DHW from Legionella-growth, which is a violation of Norwegian building code TEK17.

1:17pm - 1:29pm

Prediction of Electricity Consumption of a HVAC System in a Multi-Complex Building Using Back-Propagation and Radial Basis Function Neural Networks

Benhao Liu1, Moon Keun Kim2, Nan Zhang3, Sanghyuk Lee4, Jiying Liu5

1Department of Electrical and Electronic Engineering, Xi’an Jiatong-Liverpool University, China;; 2Department of Civil Engineering and Energy Technology, Oslo Metropolitan University, Oslo, Norway; 3Institute of Statistics and LPMC, Nankai University, Tianjin, China; 4Department of Mechatronics and Robotics, Xi’an Jiatong-Liverpool University, Suzhou, China; 5School of Thermal Engineering Shandong Jianzhu University, Jinan, China

This study examined approaches to predict electricity consumption of a Heating, Ventilation and Air-Conditioning (HVAC) system in a multi-complex building using two neural network models: Back Propagation (BP) and Radial Basis Function (RBF) with input nodes, e.g., temperature, humidity ratio, and wind speed. Predicting HVAC energy consumption of buildings is a crucial part of energy management systems. We used two main neural network models, BP and RBF, to evaluate the prediction performance of electricity consumption of HVAC systems. The BP neural network method exhibited good performance, but it exhibited relatively large fluctuations and slow convergence in the training process. In contrast, RBF exhibited relatively fast learning and reduced computing costs. The HVAC energy consumption rate of working days was higher than that of non-working days The results indicate that the prediction of HVAC energy consumption using neural networks can effectively control the relationship between the HVAC system and environment conditions.

1:29pm - 1:41pm

Investigation of work-practices, skills and everyday challenges of building operators with respect to indoor climate and energy

Jakub Kolarik1, Helle Lohmann Rasmussen2, Jacob Steen Harbo3

1Technical University of Denmark, Denmark; 2Dansk Facilities Management; 3Frederiksberg Forsyning A/S

Focus on sustainable construction brings many requirements and standards to ensure energy efficiency and high indoor environmental quality (IEQ). However, these are mainly used in design phase. Commissioning becomes increasingly common to ensure functionality when building is taken into use. However, buildings are expected to stay in use for many years. It is a building operator, who ensures that building delivers healthy and comfortable environment. It is beyond discussion that his/her skills and professional level affect building’s actual performance. The present study that had an objective to investigate work skills, experiences and professional challenges of building operators in Danish office buildings with particular focus on IEQ and energy efficiency. Thirty building operation professionals working in 23 companies were interviewed. The results showed that occupant complaints were a driving factor with respect to IEQ related measures. Building operators had a general interest in analysis of the IEQ in their buildings, but their knowledge of related standards and requirements turned up to be rather superficial. In most cases, there was a lack of a well-defined operational strategy regarding IEQ. The results show that there is a need to provide a missing link between technological part of building operation and a strategic part defining a clear goals and practices.

1:41pm - 1:53pm

Mucociliary clearance is humidity dependent–contrary to common belief: HVAC systems overstress human noses during the heating season-the consequences

Walter Hugentobler

Condair Group AG, Switzerland

Unlike all mammals including primates, the species homo sapiens spread throughout all climate zones in the 350’000 years of his evolution. Three features, unique to humans, made this possible: a flexible, multipurpose nose, sweating and clothing. Regarding the nose, anthropologic studies and comparative anatomy have verified a significant biogeographical cline [biological gradient] that evolves from low profile, relatively wide noses, where seasonal absolute humidity is high to protrusive, narrow ones, where the air contains little moisture but high dust concentrations. Together with the “nasal cycle” (abstract 1) this substantiates the assumption that the multiple tasks of our nose (protecting lower airways from desiccation, overheating, cooling, infection and pollution) is challenging and needed anatomical and physiological adaptations throughout evolution.

During the last two hundred years however, building industry imposed an unprecedented, ultimate climate challenge to our noses: heated, mechanically ventilated indoor environments, where we spend roughly 90% of lifetime since the industrial revolutions. While extreme outdoor climate conditions result in sparse population, heated and ventilated indoor conditions expose the entire population of the temperate climate zone to desert like conditions, for weeks, not for hours (see abstract 1).

Contrary to the widespread opinion, MCC efficiency, first and foremost nasal MCC, is humidity dependent. Yet the lower humidity limits of building codes are based on the assumption that MCC is resistant to very low ambient humidity. This is only supported by a couple of studies by Anderson and Procter that included exclusively young, healthy Danish students as test persons. Their studies indicate that selected young and healthy persons may support very low humidity for up to 78 hours without impaired MCC. By contrast, when including people of all ages and with common diseases, all studies (they will be presented at the conference) provided ample evidence for humidity dependence of nasal MCC.

Providing suitable indoor climate conditions for everybody is imperative. Increasing the lower relative humidity limit to 40% (building reality in winter is often 20-30%) would protect the health of all occupants and reduce the burden on public health by chronic respiratory diseases and seasonal respiratory infections.

1:53pm - 2:05pm

Development and Application of a Ventilation System based on Vertical Descendent Confluent Jets

Eusebio Conceição1, João Gomes3, Mª Inês Conceição2, Mª Manuela Lúcio1, Hazim Awbi4

1FCT - University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal; 2Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; 3CINTAL, Campus de Gambelas, 8005-139 Faro, Portugal; 4School of Built Environment, University of Reading, Reading, RG6 6AW, United Kingdom

This paper presents the development and application of a ventilation system based on vertical confluent jets. The thermal comfort and indoor air quality levels, Air Distribution Index and energy consumption are evaluated and discussed. The numerical study is carried out in a virtual chamber with dimensions of 4.50x2.55x2.50 m3. This chamber is equipped with six tables, twelve chairs, one outlet system and one confluents jets system, and is occupied with twelve virtual occupants. The inlet system has two horizontal 0.15 m diameter ducts, installed at a height of 1.8 m from the floor, which have consecutive holes in order to promote downward jets close to the side walls. The outlet system has six air ducts, located above the head of the occupants, connected to the ceiling area. The study was developed for three different airflow rates, considering winter conditions. As the airflow rate increases, indoor air quality improves, thermal comfort remains within an acceptable level and ADI improves slightly.

2:05pm - 2:10pm

Better building operation, maintenance and well-being in apartments with smart indoor climate meters

Lars Gunnarsen1, Rune Korsholm Andersen2, Göran Wilke3

1Aalborg University, Denmark; 2Technical University of Denmark; 3IC-Meter aps

The justification of energy consumption in dwellings is to maintain comfortable and healthy indoor climate. Air exchange and comfortable temperatures may also protect building structures against decay and mould growth. Expenditures in relation to building maintenance and loss of health normally by far exceeds the expenditures in relation to energy consumption. But in blocks of flats with billing for energy use in relation to individually metered consumption it is economically attractive for tenants to keep their indoor temperatures low. Their savings can become very big when temperatures are slightly lower than in surrounding flats because the walls and floors between flats are more important for the heat loss from an individual apartment than building envelope. The introduction of smart indoor climate meters of temperature, humidity and carbon dioxide concentrations is a modern alternative to energy consumption metering. The meters permit calculation of payments according to ability to maintain a healthy indoor climate.

The purpose of this paper is to examine the differences in indoor climate quality and heating expenditures between rental apartments in the same tenement before and after the introduction of smart indoor climate meters.

We analyzed heating accounts from approximately 500 apartments in three tenements. The apartments was equipped with equipment logging temperature, relative humidity and CO2. Energy use before introduction of indoor climate meters show more than a factor 15 difference between minimum and maximum payments in apartments with similar characteristics. Furthermore, preliminary results indicate that differences in energy consumption does not correlate with the measured differences in indoor temperature, humidity and carbon dioxide. These results could also illustrate a need for revision of the common recommendations regarding the preservation of energy to give a more sustainable set of guidelines, especially in apartment buildings where temperature competition between tenants potentially can damage the whole building.

2:10pm - 2:15pm

Assessment of three experimental methods for determining the emission parameters of VOCs from a solid material

Florent CARON1, Marie VERRIELE1, Romain GUICHARD2, Laurence ROBERT2, Frédéric THEVENET1

1IMT Lille Douai, Université de Lille, SAGE, 59000 Lille, France; 2French Institute of Research and Safety (INRS), Department of Process Engineering, Rue du Morvan, CS 60027, 54519 Vandoeuvre-lès-Nancy Cedex, France

Emissions of volatile organic compounds (VOCs) from solid materials directly impact indoor air quality. Their contribution to pollutant dynamics have to be integrated to indoor air simulation models. Therefore, reliable and validated experimental data are expected by modelers. The VOC emission processes from a solid material can be described by three key parameters: the partition coefficient (K), the initial emittable concentration (C0) and the diffusion coefficient (D). Three experimental methods from literature allow determining simultaneously the three emission parameters: the C-history methods operated under (i) airtight or (ii) ventilated conditions, and (iii) the alternative airtight ventilated emissions (AAVE). However, these methods have never been compared using the same material and addressing simultaneously a variety of VOCs emitted.

This work provides an experimental assessment and comparison of the three methods. Experiments are carried out using a 128 L well-mixed chamber containing a particleboard as VOC source. The chamber is connected to an online gas analyzer (Selected Ion Flow Tube-Mass Spectrometry), allowing the effective characterization of emitted VOCs. Different samples of the same material are used along experiments. Thus, after evaluating the variability of VOC emissions between samples, each method has been assessed three times to address their individual variability and reproducibility and allow proper comparisons between methods.

If the protocols of the C-history methods require shorter and easier experimental tests, they impose advanced data treatments. Moreover, contrasted and unexpected values observed between airtight and ventilated C-history methods question the influence of the aeraulic conditions on the determination of the emission parameters and the subsequent representativeness of their experimental conditions. The AAVE method definitely requires a more advanced control on the experimental conditions. Nevertheless, the protocol interestingly encompasses various ventilation regimes and the possible exhaustion of the sample. The comparison of the emission parameter values obtained from the AAVE method with the C-history methods and the literature data underlines the ability of the AAVE methods to provide more accurate and reliable emission parameters. Therefore, experimental data retrieved by AAVE methods should be privileged for implementation in simulation models.

2:15pm - 2:20pm

An overview of transparent and translucent 3D-printed façade prototypes and technologies

Marzieh Ghasemieshkaftaki, Marco Ortiz, Philomena M. Bluyssen

Delft University of Technology, The Netherlands

3D-printing has transformed traditional manufacturing, by enabling the fabrication of individually designed complex systems in a short amount of time. The building’s facade is also one of the most complex and challenging systems because it has positive impacts on controlling the built indoor environment and increasing energy-saving. Thus, the main objective of this research was to distinguish 3D-printing technologies that can improve transparency and translucency in the façade of the buildings in order to decrease artificial lighting consumption, control solar energy, and improve energy saving. A literature study was performed in this article and firstly, different types of 3D-printing techniques, and their methods for producing transparent materials were reviewed from academic databases. Then, transparent 3D-printed facade prototypes based on what was extracted from resources were identified. In order to achieve reliable resources, the Impact Factor of journals was checked. Sources that were written by an authentic author or university were selected. Moreover, about 3D-printed prototypes, the tests which were used to check their features and qualities (e.g. transparency, insulation) were studied and investigated. By analyzing prototypes, it became obvious that most of them used the FDM 3D-printing technique and Polyethylene Terephthalate Glycol (PETG) as a material to enhance natural lighting transmission. These prototypes didn’t consider the disadvantages of the FDM technique for the lighting transmission. Several 3D-printed prototypes performed like an adaptive facade and tried to control daylight and reduce discomforts such as overheating and glare. Some 3D-printed prototypes were such as glazed facades, compare to a static facade they were transparent, but compare to an adaptive facade they did not have any control over daylighting discomforts. Additionally, the energy efficiency of prototypes was analyzed and compared based on their solar gain control, natural ventilation, and daylight penetration. These prototypes attempted to improve energy-saving which ranged from applying recyclable materials to controlling solar gain.

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