bluuebunny/crossref_metadata_2025 huggingface dataset:
Science in children’s stories for elementary school
Authors: Apriliya S , Sunendar D , Mulyati Y , Sumiyadi S
Published: October 2019

Science is one of important subjects for elementary school students. It will be very pleasant for students if the science is presented in an interesting form. One of them is through children’s stories. This study aims to explain the content of science in Indonesian children’s stories. The data source of this study is 56 stories of children at the national level competition from 2011-2014. The research data was obtained by repetitive reading techniques, notes, and classifying text (words, phrases, and sentences) based on the category of science. Results showed that there is science content in several children’s stories. However, the science texts presented are not based on scientific knowledge, but are based on observations in everyday life. In addition, the scientific content presented in the story is not entirely in accordance with the science curriculum in the elementary schools. The implication is that teachers can use science content in children’s stories as an alternative to attract elementary school students to enjoy science.
ICT training curriculum for primary school teachers
Authors: Syahid A A , Isrokatun I , Nugraha D
Published: October 2019

The advancement of this modern day has required primary school teachers to utilize Information and Communication Technology (ICT) devices in the classroom. Therefore, it is imperative that teachers possess the skills to use ICT. Several studies have shown that teaching process (instruction) using ICT provides more optimal result for the students. This paper will discuss the result of a study aiming to develop an ICT training curriculum for professional teachers. The data for this study has been collected since 2017 to 2018 through surveys to explain need analysis of ICT skill for teaching. The product of this study is a curriculum structure in the form of training materials that primary school teachers need to improve their skills in utilizing ICT in teaching activities. This training curriculum is expected to lead to an effective training because it is developed based on teachers’ needs in implementing ICT in primary school.
A Comparison of Central composite design and Modified Taguchi approach to optimize the process parameters
Authors: Kumar G Charan , Rajyalakshmi K.
Published: October 2019

Second order rotatable design (SORD) concepts will be more useful in developing the appropriate empirical relations. As the number of input variables are increasing (with the assigned levels to each variable), there is a need to conduct more number of experiments which may sometimes be practically impossible. Taguchi designs can solve the problem with less number of experiments and provides complete information useful for the applications of second order rotatable designs. This article provides a comparison of Central composite design and modified Taguchi approach and its validation by tracing the optimum process parameter on the experimental design. It is possible to get the required information and the expected range of process parameters from modified Taguchi design.
Variable mesh non polynomial spline method for singular perturbation problems exhibiting twin layers
Authors: Phaneendra K , Emineni Siva Prasad
Published: October 2019

In this paper, we descend a variable mesh finite difference scheme based on non polynomial spline approximation for the solution of singular perturbation problems with twin boundary layers. We develop the discretization equation for the problem using the condition of continuity for the first order derivatives of the variable mesh non polynomial spline at the interior nodes. The discrete invariant imbedding algorithm is utilized to solve the tridiagonal system obtained by the method. Endeavor examples are illustrated and maximum absolute errors in comparison to the other methods in the literature are shown to vindicate the method.
Countably many positive solutions for a coupled system of fractional order BVPS
Authors: Prasad K.R. , Rashmita M.
Published: October 2019

In this paper we establish the existence of countably infinitely many positive solutions for coupled system of two point Riemann-Liouville integral fractional order boundary value problems. The main results are established by using the fixed point index theory in cone on a Banach space with increasing homeomorphism and positive homomorphism.
Analysis of a M/M/1 Queueing System with Two-Phase, N-Policy, Server Failure and Second Optional Batch Service with Customers impatient behaviour
Authors: Devi V N Rama , AnkammaRao A , Chandan K
Published: October 2019

In this paper an M/M/1 queueing system with server vacation, Startup, breakdowns and second optional service with impatient customer behavior is considered. All the customers will be given unique type of individual service in the first phase and then second phase service will be provided on option of the customer. We obtain some important system characteristics, such as the number of customers in the system, the probability that the server is idle, busy and broken down states, the expected waiting time in the system. Sensitivity analysis is also conducted with various parameters on system’s performance measures.
Efficient Identity-based Signature Scheme with Message Recovery
Authors: James Salome , Reddy P Vasudeva
Published: October 2019

Digital signature is one of the important primitive of public-key cryptography and has become an essential technique in providing security services in modern communications. Due to the limitations imposed by both the communication bandwidth and computational power of wireless communication devices, signature schemes with less bandwidth and less computational cost are desirable for practical applications. Signature schemes with message recovery provide a feature that the message is recoverable from the signature and hence does not need to be transmitted separately for signature verification. Recently many signature schemes with message recovery have been designed in traditional as well as Identity based settings and most of the schemes are constructed using bilinear pairings over elliptic curves. Nevertheless, the computational cost of a pairing is more expensive and is higher than the scalar multiplication. Thus, signature schemes without pairing would be more appealing in terms of efficiency. In this paper, we propose an efficient identity-based message recovery scheme without pairings. In our scheme the message itself is not required to be transmitted together with the signature and so it turns out to have the least data size of communication cost. Also, we compare our scheme with the existing ID-based signature schemes with message recovery in terms of computational and communicational point of view. With the pairing-free realization, the proposed scheme is efficient and applicable for resource constrained devices.
Coding theory on Pell-Lucas p numbers
Authors: Sundarayya P. , Prasad M.G. Vara
Published: October 2019

In this paper, we developed a new coding and decoding method followed from Pell-Lucas p numbers SpAn. We established the relations among the code matrix elements for p = 1 and i=1, error detection and correction for this coding theory. Correction ability of this method is 93.33% for p = 1,i=1 and for p = 2,i=2 the correction ability is 99.80%. In general, correction ability of this method increases as pincreases.
Analysis of a Markovian queueing system with single working vacation and impatience of customers
Authors: Laxmi P. Vijaya , Kassahun T. W. , Bhavani E. Girija
Published: October 2019

In this paper, we study an infinite capacity single server Markovian queue with a single working vacation and reneging of impatient customers in the queue during working vacation period. Customers arrive to the system following a Poisson distribution. The server goes to vacation when the system is empty and stay in vacation for a random period of time that is exponentially distributed. During the working vacation period, the server still continue providing service with a slow service rate. After the completion of the vacation, the server returns back to the regular service period and continue providing service with the regular busy period service rate if there are one or more customers in the system or it will stay idle until a new customer arrives to the system. During working vacation, customers in the queue get impatient and renege from the system and the reneging time is assumed to follow an exponential distribution. The system is modeled as a quasi-birth-death process and the stationary probabilities of the model are obtained using probability generating function approach. Some numerical analysis is also carried out to show the effect of some of the parameters on some selected performance measures of the system.
On the Operator Partial Semirings of Partial Γ-Semiring
Authors: Mala M Siva , Rao P V Srinivasa , Kumar K Kiran
Published: October 2019

A partial Γ-semiring is a structure possessing an infinitary partial addition and a ternary multiplication, subject to a set of axioms. The partial functions under disjoint-domain sums and functional composition is a partial Γ-semiring. In this paper we introduce of notions of left/right operator partial semirings of a partial -semiring and obtained a correspondence between the partial ideals of partial Γ-semiring R and its operator partial semirings.
Bianchi type-II, VIII and IX perfect fluid cosmological model with domain walls in f(R, T) gravity
Authors: Rani N Sandhya , Santhi M Vijaya
Published: October 2019

This paper deals with the Bianchi type - II, VIII & IX metrics in presence of domain walls in the frame work of the modified f
(R,T) theory of gravitation, where R is Ricci scalar and T is the trace of energy momentum tensor. Also, some important features of the models, thus obtained, have been discussed.
Modified Holographic Ricci Dark energy Cosmological Models in f (R, T) Gravity
Authors: Sireesha K. V. S. , Rao V.U.M.
Published: October 2019

We have investigated spatially homogeneous anisotropic Bianchi type-II, VIII & IX cosmological models in the presence of pressure less matter and modified holographic Ricci dark energy in the frame work of f(R, T) gravity in the context of late time accelerating expansion of the universe. The solutions of the field equations obtained using (i) a relation between metric potentials and (ii) the modified holographic Ricci dark energy. We have determined the cosmological parameters, namely, EoS parameter, matter energy density, anisotropic dark energy density, deceleration parameter. We discuss some physical and geometrical properties of the obtained models which are found to be consistent with recent observation
Optimal design of looped water supply network by GA-NLP hybrid approach
Authors: Prasad A Srinivasa , Krishna K Leela
Published: October 2019

Any Municipal distribution system consists of pipe network, valves and pressure generating facilities etc. Around 70% of total cost of any water distribution system is towards cost of pipe network only. Therefore, the cost of pipe network is to be reduced by selecting the appropriate lengths of candidate diameter pipes between the nodes in a pipe network.

In the present study, a municipal looped water distribution network is designed for least cost by Genetic Algorithm – Non Linear Programming (GA-NLP) hybrid approach. In the present study, optimal lengths of sub pipes of various discrete diameters (sizes) available in the market making the link between the nodes are obtained by minimising the total cost of pipe network. In order to obtain the optimal solution of a looped network, non - linear hydraulic analysis and optimization of network is to be performed. In this study, non - linear hydraulic analysis is made a part of optimization by adding loop head loss and node continuity equations as constraints to the objective function. The model developed is solved by GA-NLP hybrid approach in MATLAB. Near optimal solution obtained by GA is taken as initial solution of NLP for obtaining optimal solution. By adopting GA-NLP hybrid approach, convergence is faster when compared to GA avoiding the complexity in selection of suitable trial values of GA parameters.

Many researchers applied different techniques like linear programming, integer linear programming, linear programming gradient method and branch & bound algorithm etc. and optimized the looped pipe network by minimizing the cost. The results obtained by proposed model are compared with that of other investigators and found to be superior. It is also concluded that the proposed model may be applied to any larger municipal looped pipe network through demonstration by applying proposed model to a case study of Rajiv Gandhi Nagar of Guntur Municipal Corporation.
Katowski-Sachs generalized ghost dark energy cosmological model in Saez-Ballester scalar -tensor theory
Authors: Vinutha T , Rao V U M , Bekele G
Published: October 2019

In this paper we have studied the Kantowski-Sachs (KS) space time filled with generalized ghost dark energy (GGDE) and dark matter in the Saez-Ballester theory of gravitation. The equation of state (EoS) parameter of dark energy (ωλ
) has been formulated as a function of cosmic time and shows quintom like behavior. The properties of density of dark energy (ρλ
) and the density of dark matter (ρm
) indicate the accelerated expansion of the universe. The pressure of the dark energy is negative at present and late time evolution of the universe indicating the accelerated expansion of our universe during these periods. The physical and geometrical aspects of the statefinder parameters (r, s), squared speed of sound

(

υ
s
2

)

and

ω
λ

−

ω
′

λ

plane are also discussed.
Five Dimensional Little Rip Cosmological Models In General Relativity
Authors: Vinutha T. , Kavya K. Sri , Kumari G. Sree Devi
Published: October 2019

In this paper, we have investigated flat Friedmann-Robertson-Walker type Kaluza-Klein model in the presence of ideal fluid with quadratic equation of state(EoS) with time dependent parameters ω(t) and (Λt). We have investigated the properties of ω(t) and found that for Little Rip model ω(t) = −1 and for Pseudo Rip model ω(t) <
−1. Also, we have studied behaviour of Little Rip(LR) and Pseudo Rip(PR) for dark energy. For obtained LR and PR models we have estimated the disintegration time.
Bianchi type V Ih Bulk-Viscous String Cosmological Model in f(R) Gravity
Authors: Santhi M. Vijaya , Sobhanbabu Y. , Rao B. J. M.
Published: October 2019

In this paper, we derive f(R) gravity field equations with the help of a spatially homogeneous and anisotropic Bianchi type-V Ih
space-time, in the presence of a bulk-viscous fluid, containing one-dimensional cosmic strings. Here we obtained the solutions of the field equations, under some specific plausible physical conditions. In particular, cosmological model with bulk-viscous strings in f(R) theory of gravity is obtained by using the special law of variation for Hubble’s parameter proposed by Berman (Nuovo Cimento, B74, 182 (1983)). Some physical and kinematical properties of the models are also discussed.
Fuzzy Kernel Based Effective Clustering Techniques in Analyzing Heterogeneous Databases
Authors: Kannan S R , Siva M , Devi R , Ramathilagam S , Last Mark
Published: October 2019

The aim of this paper is to introduce an effective fuzzy clustering technique based kernel function to find appropriate subgroups in heterogeneous databases. This paper introduces the effective fuzzy clustering that incorporates weighted bias field information, kernel distance, possibilistic memberships and fuzzy memberships into memberships equation and prototype equation. The effectiveness and efficiency of the proposed clustering techniques have been shown through the experimental results on benchmark heterogeneous databases.
An empirical study on shortest path for Graph clustering in Network analysis
Authors: Charan Kumar G. , Latha G. Shobha
Published: October 2019

Network theory deals with the study of graphs in which nodes connected by branches. It helps to determine the shortest route between two places, time schedule for the activities of a project and minimum cost flow in pipeline networks. In the present paper, we with the existing algorithms based on network theory and finding the shortest path from use the cluster algorithms to find the can be compare one to another and also shortest paths when the clusters are grouping based on cluster analysis the results which we obtain observed that the similarity levels of single, average and complete linkage methods. By applying the existing algorithms based on graph theory can analyze the shortest path from one to another where as clustering provides the shortest path as well as the similarity index for standardized and non-standardized variables.
Innovative public procurement (IPP) – Implications and potential for zero-emission neighborhood (ZEN) projects?
Authors: Hamdan Hasan A. M. , de Boer Luitzen
Published: October 2019

As a component of the urban fabric system, zero-emission neighborhood (ZEN) projects represent an opportunity to boost the sustainable performance of cities. However, overlooking the potential of different actors or underestimating the complexity of interactions among them may threaten the projects themselves. Public procurement is a powerful tool that potentially enables national and local authorities to achieve sustainable development goals while procuring necessary products and services. This paper aims to understand the potential of innovative public procurement (IPP) to reduce some of the project complexity in ZEN. Besides literature on sustainable neighborhoods (SN), empirical insights are drawn from an ongoing ZEN project to map the primary sources of complexity in such projects. Afterward, the potential for dialogue with suppliers is mainly discussed in light of these sources. Our findings suggest that using IPP may assist in reducing the complexity imposed on ZEN projects.
Validation of a Flexibility Assessment Methodology for Demand Response in Buildings
Authors: O’Connell S , Reynders G , Seri F , Keane M
Published: October 2019

Flexibility in Buildings is an integral part of the solution to address the electrical grid’s challenges of grid balancing and renewable generation hosting capacity. One of the main barriers to greater participation of commercial and residential buildings in demand response schemes is the complexity and cost associated with assessing the flexibility of buildings. To overcome these barriers, an early stage flexibility assessment methodology was developed to provide stakeholders with actionable information in a concise and relevant way, so they can effectively evaluate the flexibility of their building and negotiate with aggregators for demand response participation. This paper validates the early stage flexibility assessment methodology in multiple buildings, demonstrating its ease of implementation and scalability. The validation was conducted at five pilot sites, in different geographical regions, activating a range of flexible sources through experiments on site.
Energy performance evaluation of a nearly Zero Energy Building and the reasons for the performance gap between expected and actual building operation
Authors: Loukou Evangelia , Heiselberg Per K. , Jensen Rasmus L. , Johra Hicham
Published: October 2019

As energy standards focus on reducing energy use in new buildings, attention is drawn to the gap between the expected and actual building operation and energy performance. This performance gap can be associated with the building construction, its systems, its unbalanced operation, the assumptions on occupancy profiles during the design phase, or the users’ interaction with the systems’ operation and control. This work focuses on a nearly zero-energy (nZEB) single-family house located in central Denmark. The analysis of indoor environment and energy use is based on year-long data monitoring. The reasons for the deviation between the expected and actual energy use are suggested. The indoor environmental quality is analyzed to verify the compliance with the standards. The European recommendation for the yearly primary energy use of new single-family houses is 50 – 65 kWh/m2. For the current case, the simulation tool Be18 gives a result of 30.8 kWh/m2 for the design phase. However, the actual energy use is measured to be 58.2 kWh/m2. The sensibility of nZEBs to such imbalances can lead to houses that do not function as intended. It is thus crucial to investigate further the causes of these disparities in order to bridge the gap between expected and final energy use in dwellings.
Business models for nZEB renovation of small wooden buildings
Authors: Kvellheim Ann Kristin , Damman Sigrid , Lien Anne Gunnarshaug
Published: October 2019

To achieve a sustainable building stock, it is necessary to focus on existing as well as new buildings. New houses built according to the Norwegian building code are close to nZEB (near Zero-Energy Building) level, but existing buildings contribute a significant share of the energy consumption, and the difference between new and older houses is increasing. As the renovation rate is low, it is important to include ambitious energy upgrading once a renovation project is undertaken. So far, however, there is almost no market for nZEB renovation of small wooden buildings. These buildings are challenging to renovate, and even more challenging to do so with ambitious climate targets. In effect, only half of the renovations in Norway include energy renovation. The demand for ambitious renovation depends on a value proposition that is understood by the customer. Novel and well-designed business models can be central tools for achieving this. In this paper, existing and potential business models for renovation of wooden housing are identified and analysed.

This paper is based on the “Energy upgrading of wooden dwellings to nearly zero energy level” (OPPTRE) project. One of the activities for researchers, industry and public partners in OPPTRE is to identify, analyse and assess current business models, and develop novel approaches through collaborative workshops and interviews. The results are documented and elaborated upon by the research team before the next step, which is to test the most promising models.

Previous research indicates that only a small share of Norwegian enterprises have changed their business model over time. Two of the reasons for this are lack of critical reflection on existing business models and fear of changing the status quo. A third reason is lack of knowledge of how to manage the transformation process. In the process of identifying existing and developing novel business models, the partners in OPPTRE explore new opportunities to promote ambitious energy upgrading. Their commercial performance is likely to increase through the focus on business model design. New business models may also help increase the uptake of innovative energy solutions in the renovation market for small wooden buildings.
Wood burning habits and its effect on the electrical energy demand of a retrofitted Norwegian detached house
Authors: Felius L. C. , Thalfeldt M. , Georges L. , Hrynyszyn B. D. , Dessen F. , Hamdy M.
Published: October 2019

Using firewood as a space heating source is a popular solution in Norwegian housing and can significantly reduce the electrical energy demand of houses. This study analysed habits and reasons for using a wood stove from survey data. From this, typical behaviour patterns were defined. These patterns were imported into a building performance simulation model of a typical Norwegian single-family detached house to evaluate the impact of the stove user behaviour on the electrical energy demand and on the overheating risk. Results showed that up to 32% of the electrical energy demand for space heating can be saved using a wood stove. The number of overheating hours increased when the wood stove was used more frequently. However, it decreased after full renovation because the stove is used less often, as the total space heating demand decreases and the indoor temperature drops less often below the temperature set-point when the stove is started. Active use of the wood stove is effective as retrofitting measure when the aim is to save electricity or fossil fuels. Nevertheless, if the stove power is not adapted to the building, it can be challenging to maintain a comfortable temperature in the room.
Designing a ZEN Campus: An exploration of ambition levels and system boundaries
Authors: Skaar Christofer , Solli Christian , Vevatne Jonas
Published: October 2019

The Norwegian University of Science and Technology (NTNU) is gathering from dispersed locations to one central campus at Gløshaugen, requiring an estimated 92 000 m2 new buildings and upgrading 45 000 m2 of existing buildings. NTNU has high environmental ambitions for the new campus, including zero-emission ambitions. This paper explores system boundary definitions and ambition levels in a Zero Emission Neighbourhood (ZEN) context. A key element is a plus energy campus that provides a surplus of renewable energy in the operational phase, that can compensate the carbon footprint of buildings, infrastructure and mobility. Preliminary energy and carbon analyses of the campus have been performed A key result is an overview of design choices and methodology choices for concept stage calculations for a zero-emission campus. Six system boundaries have been defined, with the production to consumption ratio varying from 19 % to 132 %. The lowest includes all buildings, the highest includes production from all buildings, but consumption only from new and renovated buildings. The main finding is that it is possible to realise a plus energy campus for new and renovated buildings, but not including non-renovated buildings. A plus energy campus requires a combination of PV and seasonal energy storage.
Defrosting and Frost Protection Measurements of Heat Recovery in Cold Climate
Authors: Johansson D , Wahlström Å , Dahlblom M
Published: October 2019

The installation of technical solutions for heat recovery from the ventilation air is a very important step, both with respect to improving the indoor climate and as an energy-saving measure. Ventilation without heat recovery use a substantial part of an entire building’s heating use, especially if the building is a low energy building. To realize a large implementation of heat recovery property owners must increase their knowledge about how these systems work and they must be able to rely on them functioning properly. The function and performance of a ventilation system when it comes to heat recovery can be a problem as soon as temperatures drop far below zero. When freezing occurs some form of defrosting is required and this can lead to indoor climate problems and to little or no heat recovery being obtained, which will reduce the energy efficiency and, at the same time, may compromise moisture safety. The goal of this project is to increase knowledge about how heat recovery systems for residential buildings with respect to defrosting and frost protection measures in heat exchangers. The knowledge can thereafter be used to develop effective defrosting strategies and frost protection measures so that the energy use and power requirements are minimized. Measurements were performed for heat recovery systems placed in dwellings in north Sweden to investigate occurrence of frost formation. The paper will present these measurements and some comparing simulations which can serve as a basis for further development of good defrosting strategies.
A Norwegian zero emission neighbourhood (ZEN) definition and a ZEN key performance indicator (KPI) tool
Authors: Wiik Marianne Kjendseth , Fufa Selamawit Mamo , Andresen Inger , Brattebø Helge , Gustavsen Arild
Published: October 2019

Within the Norwegian Research Centre for Zero Emission Neighbourhoods (ZEN) in smart cities, a definition for achieving zero emission neighbourhoods will be developed and tested against nine pilot areas. The ZEN definition considers a series of assessment criteria and key performance indicators (KPI) under seven categories; GHG emissions, energy, power/load, mobility, economy, spatial qualities and innovation. This paper presents the first draft of the ZEN definition, and discusses some of the opportunities and challenges in implementing assessment criteria and KPIs (ZEN metrics) into a ZEN KPI tool. This paper briefly presents the ZEN pilot areas and maps out existing tools used by ZEN stakeholders for the documentation of ZEN metrics. The paper goes further by presenting a ZEN KPI tool conceptual framework for the implementation of the ZEN definition in ZEN pilot areas and outlines a specification for the future development of a ZEN KPI tool. Finally, the paper presents further work for the development of a ZEN KPI tool.
Using residential buildings to manage flexibility in the district heating network: perspectives and future visions from sector professionals
Authors: Andersen P V K , Georg S , Gram-Hanssen K , Heiselberg P K , Horsbøl A , Johansen K , Johra H , Marszal-Pomianowska A , Møller E S
Published: October 2019

Intermittent energy resources challenge the ways in which the existing energy system operates. Studies suggest that residential buildings can provide a flexibility service for district heating (DH) systems. This technique involves load shifting by heating buildings to higher temperatures at times when energy is more readily available, thus diminishing heating needs at times of peak demand or when energy is scarce. Based on three Future Workshops (FWs) where DH professionals and other relevant DH stakeholders participated and discussed this topic, this paper reports on the extent to which these actors see energy flexibility as a realistic future development, and on what they see as key potentials and challenges in that regard. Preliminary results indicate that the mix of the actors and the specific local context greatly influence how this topic is understood, emphasizing the importance of including local context in investigations of energy flexibility. FW participants included representatives from DH companies, municipalities, building associations, technology developers, etc. The FWs were conducted at three different localities of Denmark: Copenhagen, Aalborg and Sønderborg, i.e. the national capital, a regional capital and a smaller city, respectively.
Efficiency of BIPV system – Field study in Norwegian climate
Authors: Gullbrekken Lars , Bunkholt Nora Schjøth , Grynning Steinar , Bellman Martin , Kvande Tore
Published: October 2019

Use of solar cells (PV) and solar collectors are key remedies in buildings where a large part of the energy supply should be based on renewable energy. The aim of this work has been to evaluate calculated and measured solar production of two identical BIPV roofs located at the ZEB Living Laboratory situated at NTNU-campus in Trondheim. Temperature, irradiance and wind speed and direction at the rooftop of the building have been monitored since the construction of the house. There was found a large difference in energy production of the northern roof section and the southern. One possible explanation is shading of the northern roof because of low solar azimuth during the measuring period. In order to avoid such disadvantages, design of the PV-roofs should be considered early in the design phase of the building project. A small difference was found between the hourly measured and the calculated values of the PV performance based on the monitored local climate data. Use of generic climate data expect to cause a larger difference between measured and simulated energy performance due to lack of consideration to local conditions.
Relation between daylight availability and electric lighting in a single-family house
Authors: Lobaccaro G , Savarino M , Goia F , Fabrizio E
Published: October 2019

Daylight availability is an important aspect that can potentially improve both the quality and the energy performance of buildings. However, it is not always straightforward easy to assure that an increase in the daylight availability leads to a reduction of electric energy use for artificial lighting. In this study, experimental measurements and numerical simulations were conducted to analyse the relation between the uses of artificial light and the daylighting availability for different groups of users who lived for one month each in a Zero Emission Building single-family house located in Trondheim, Norway. The use of electric lighting and the outdoor environment conditions (irradiance and illuminance on the horizontal plan) were recorded through advanced daylighting simulations, carried out with DIVA-for-Rhino, the daylighting availability during the periods of occupancy was then reconstructed, using as input data the outdoor environmental variable recorded during the experimental analysis. The results show that the coefficient of correlation between daylight availability and the artificial light is in general low and the use of artificial lighting seems to be largely independent from the availability of natural light.
Geo-Solar District Heating – Lessons Learnt from a not Realised Project
Authors: Schmidt Dietrich , Stroh Kilian
Published: October 2019

For the new housing area with approx. 130 low energy residential houses, located in Kassel, Germany, various supply concepts are investigated. Main objective of the project is the development of an innovative and optimised heat supply concept based on renewable energies and a low temperature district heating for later realisation.

During the course of the project several heat supply concepts have been investigated and compared to give an input to the decision and realisation process. A promising heat supply concept is based on a central ground source heat pump in combination with a low temperature district heating (40°C supply temperature) for space heating and decentralised solar thermal systems for domestic hot water preparation. The advantages of this supply variant are comparable low annual heating costs and about 60% lower CO2-emissions in comparison to the reference system (decentralized air / water heat pump with solar thermal system).

Due to time constrains it was decided not to realise the above mentioned energy concept. However, the research project took up the task to investigate the transferability of the concept in technological and economical perspectives to other locations and boundary conditions. From the results of the study the importance of a very high connection rate can be highlighted. Also the question of the particular business models for such capital demanding projects (high investment costs for the heating grid vs. low energy demand/sales) has been regarded.
Latent heat storage for centralized heating system in a ZEB living laboratory: integration and design
Authors: Sevault Alexis , Bøhmer Fabian , Næss Erling , Wang Liang
Published: October 2019

The ZEB Lab project, coordinated by SINTEF and NTNU, aims at building a ZEB (Zero Emission Building) in Trondheim (Norway) in 2019, to be used both as office building and living laboratory. An innovative latent heat storage (LHS) unit using phase change material (PCM) will be integrated in the centralized heating system. The LHS unit will be able to store excess heat from various heat sources connected to the heating system, when they are not required for space heating. One challenge is to make use of the full potential of the PCM latent heat to have a compact and effective unit, while the unit itself should have a low associated CO2-footprint. The LHS system consists of two units designed for a total heat storage capacity of 0.6 MWh, corresponding to the heat needed on top of the heat pump to cover for up to 3 consecutive days in the coldest period of the year, with a maximum combined effect of 26 kW. A bio-based wax is used as PCM with melting temperature 37 °C and measured latent heat 198 kJ/kg. Dynamic system modelling is used to support the design of the LHS unit and ensure sufficiently high heat transfer rates.
On the relation of thermal comfort practice and the energy performance gap
Authors: Hellwig Runa T
Published: October 2019

Recent research results from different countries show that although energy efficiency measures in buildings indeed led to lower energy use in buildings, there is a performance gap between the calculated energy use and the actual measured energy use in energy-efficient houses, leading to a higher energy use than predicted. Thermal comfort related behaviour is one out of manifold reasons contributing to this performance gap. Thermal comfort requirements are based on objectively measurable parameters. A number of contextual factors impact an individual’s thermal comfort perception and preference. Technological opportunities and material arrangements offer several ways to conditioning indoor environments. Research shows that they shape the occupants’ thermal comfort attitudes. Over time, technology as conditioning practice and insulation has led to different thermal comfort practice in buildings contributing to this performance gap. As humans show an excellent adaptation potential towards a wide range of temperature, enabling them to adapt to diverse climates but also seasonally, it follows also the adaptation process can work in the opposite direction. Hence, that with reduced exposure to outdoor weather and more narrow temperature ranges inside building humans might also adapt to indoor thermal conditions and get more sensitive to small indoor temperature changes, leading probably to higher indoor temperature over time (“indoor exposure rebound”). As our energy conservation efforts of the recent years show less effects than expected, it seems that the two mainly applied sustainability strategies efficiency and consistency have limited effects as they are affected by rebound phenomena. Sufficiency, as the third sustainability strategy, is not yet a generally accepted strategy. It refers to what has been described as “the right measure”. The question of what would be “the right measure” of indoor thermal comfort, meaning what thermal conditions would be sufficient, can be raised. Based on a discussion of findings from literature, it will be concluded that there is a need for a new thermal comfort thinking in climates which have the need for seasonal or all year round active conditioning leading to a more sufficient conditioning practice.
Case study of personal heaters in a Plus energy building – Simulations of potential energy savings and results from a field test
Authors: Lassen N.
Published: October 2019

Personal Comfort Systems (PCS) for heating, such as foot warmers, heated chairs and infrared heaters, can compensate for a lowering of up to 10°C in ambient temperatures in a heating situation. They are found to lead to a significant increase in occupant satisfaction with the thermal environment, as they enable for a personalized thermal environment. In this way, the use of PCS systems can ensure occupant satisfaction while widening the temperature dead-band, or difference between heating and cooling set-points in buildings. Several field studies from North America have indicated that the average dead-band between heating and cooling set-points is between 1 and 2 °C, leading to considerable amounts of energy used for over-heating and overcooling. This kind of systems may therefore be an important contributor towards Plus energy buildings, but they are seldom used. The objectives of this study were (1) to test PCS heaters in a modern Norwegian office environment and see how they are appreciated by office workers and (2) to investigate how large energy savings such systems can contribute to in a Plus energy building. Powerhouse Kjørbo was selected as a case building for the study. Potential energy savings were calculated using energy simulations. The results in this case study were not able to confirm an increase in occupant thermal acceptability rate due to the use of a PCS heater. Interviews of occupants however suggest that PCS heaters are a good solution for improving the satisfaction of the limited number of occupants who have special needs, preferences or are located in a place with lower temperature. In buildings with an effective heating source, such as ground source heat pumps, PCS solutions are not likely to contribute to notable energy savings. In an indirect way, they may however still contribute toward realizing Plus energy buildings as PCS systems can help relax the demands set to other climate installations in the building. This again can allow the use of more environmentally friendly solutions such as utilization of thermal mass, temperature stratification and natural ventilation. They can also reduce installation costs by eliminating the need for more complicated and costly HVAC systems.
The design process for achievement of an office living laboratory with a ZEB standard
Authors: Time Berit , Engebø Atle , Christensen Morten , Dalby Ola , Kvande Tore
Published: October 2019

ZEB Laboratory is a full-scale office building with a ZEB-COM ambition, searching a high degree of flexibility and where components and technical systems can be modified for research purposes. Project delivery of a living laboratory with a ZEB standard is not an easy task. The implementation of the ZEB method in a partnering contract as a project delivery model has been developed. This paper describes and elaborate the development of the project delivery and design process for ZEB Laboratory seen by the client. The ZEB Laboratory design and procurement process has given valuable insight and experience into the use of partnering and collaborative elements for planning and production of ZEB buildings.
Assessing buildings’ absolute environmental sustainability performance using LCA focusing on climate change impacts
Authors: Ohms Pernille , Andersen Camilla Ernst , Rasmussen Freja Nygaard , Ryberg Morten , Hauschild Michael , Birkved Morten , Birgisdottir Harpa
Published: October 2019

The building sector is of major concern when seeking to reduce the environmental impact of our society. A common tool often used in certification systems for quantification of environmental impacts is Life Cycle Assessments (LCAs). LCAs are traditionally used for relative comparisons, i.e. to assess whether one product or service performs better than another. Recently, a method for absolute evaluations based on the Planetary Boundaries, was coupled with LCA in order to define the boundary between environmental sustainability and unsustainability. In this study Planetary Boundaries-based Life Cycle Impact Assessment method has been applied to a case study of six single family stand-alone dwellings to assess whether these buildings can be considered absolute sustainable relative to the Planetary Boundaries. The results from the assessment indicate that irrespective of the design strategy used for the six houses and future increase in the use of renewables for electricity and heat production, it is unlikely that any of these houses can be regarded as sustainable in absolute terms. This underlines that more radical changes are needed in the way buildings are constructed and used in order for buildings to become environmentally sustainable.
Co-Creation of Positive Energy Blocks
Authors: Ahlers Dirk , Driscoll Patrick , Wibe Håvard , Wyckmans Annemie
Published: October 2019

A main challenge in building carbon-neutral built environments is the ability to scale and replicate solutions. We examine how to develop low-carbon neighbourhoods and districts, while aiming at climate-friendly and sustainable livable urban environments. We take a view that not only scales up individual building solutions, but embraces the added complexities arising from the scale change and utilizes them for a novel approach. It includes a strong focus on co-creation and open innovation to develop sustainable solutions.

In this contribution, we present the approach of the +CityxChange project in implementing Positive Energy Blocks (PEB) through a European H2020 project from the topic of Smart Cities and Communities. A PEB comprises several connected buildings that have a averaged yearly positive energy balance between them. This definition excludes embodied emissions, but allows to focus on the infrastructure and systems between buildings as part of the built environment, and ways to implement and incorporate them within existing cities. The +CityxChange approach relies on co-creating Europe-wide deployment of Positive Energy Districts, with Integrated Planning and Design, Creation of a Common Energy Market, and CommunityxChange with all stakeholders of the city.
Building Bioclimatic Design in cold climate office buildings
Authors: Ness M C , Andresen I , Kleiven T
Published: October 2019

Building Bioclimatic Design (BBCD) understands architecture as a filter between outdoor climate and indoor comfort. This way, it encourages the exploitation of freely available climatic resources, before adding any HVAC system. Therefore, BBCD represents a fundamental strategy for improving energy efficiency in buildings. The climate / comfort comparison in building design determines the passive strategies that are most suitable for a specific climatic context, as well as the level of architectural complexity. In cold climates, it would suggest the use of compact shapes and extremely airtight and insulating envelopes, in order to minimize heat losses while maximizing solar heat gains. However, when combined with high internal gains, these measures might cause overheating problems in the warm seasons. That is the case of office buildings, where cooling equipment is included as default even in cold climates, drastically increasing their energy consumption. It is therefore becoming a necessity to consider here the adoption of passive cooling strategies once identified with warmer climates. The aim of this research is to explore how the theories and tools for BBCD could be applied to cold climate office buildings. In order to study the effect of the different climatic contributors, we will use Building Performance Simulation to analyse relevant cases with EnergyPlus (in combination with DesignBuilder). This will in turn help drawing suggestions on how to adapt the Building Bioclimatic Chart (BBCC) for its application to cold climate office buildings in practice. It is well known that the earlier we apply the measures for energy efficiency, the greater their effect and with higher degree of integration. The BBCC is used in the pre-design phase to determine the most suitable passive strategies for climate adaptation and control, informing the design as early as possible along the process. This study can contribute to the development of zero emission neighbourhoods in cold climates, by improving the energy efficiency of their buildings. Additionally, it complements the existing research in BBCD by extending its application to cold climates and office buildings.