Search

[Display omitted] • A hierarchical approach for automatic layout of an underfloor heating system is proposed. • The routing problem is formulated as a shortest path problem in a proper routing graph. • An order relation is defined to separate the intersecting paths. • A depth-first layout algorithm based on recursion is developed to solve the coverage path planning problem. The layout of an underfloor heating system determines its heating performance. Conventionally, the design is completed by qualified experts using professional software, but this method is inefficient and heavily relies on the experts' previous experience. This paper proposes a hierarchical approach for the automatic design of underfloor heating systems aimed at residential buildings, and the underfloor heating layout problem is decomposed into a routing problem and coverage path planning problem. First, the routing problem is formulated as a shortest path problem in an appropriate routing graph and solved to provide the routing of pipes for further coverage. Subsequently, a depth-first layout algorithm is developed to recursively simplify the coverage path planning problem to obtain the basic rectangle layout, achieving uniform coverage of the given layout zone. Simulation results on two houses show that, unlike one popular commercial platform, the proposed approach generated feasible solutions in all 13 test instances. The new method improved the minimum temperature, average temperature, average percentage of nodes greater than 30 °C, and total energy efficiency by 3.18 °C, 0.79 °C, 3.23%, and 4.19%, respectively, with a lower variance on average. These improvements lead to a higher coverage rate, more even thermal distribution, and stronger robustness under flexible parameter selection. [ABSTRACT FROM AUTHOR]

Model predictive control (MPC) has been studied in the building science realm for about three decades. However, the following two aspects of the building control have not been studied thoroughly in MPC research. One is the impact of the mixed-mode cooling system on the active heating ventilation and air conditioning (HVAC) energy consumption, and the other is the differences of individual thermal comfort preference and its impact on energy. This paper proposes an occupant-oriented mixed-mode EnergyPlus predictive control system to optimize HVAC energy consumption while meeting the individual thermal comfort preference. A web-based dashboard is implemented in the test-bed building for three months to collect individual thermal comfort preference data. The data analysis results suggest that occupants have various tolerances and preferences about thermal comfort. The simulation results show that, during one week of a typical swing season, the mixed-mode system further reduces the active HVAC energy consumption, and the diversified occupant thermal comfort preference has significant impact on HVAC energy consumption. [ABSTRACT FROM AUTHOR]

This paper quantifies green roofs energy savings which is a challenging topic, namely in Mediterranean climate with distinct heating and cooling seasons. The thermal behavior of a green roof case study in Lisbon, Portugal, was assessed through an experimental campaign during heating and cooling periods of the year of 2013. These experimental results were then used to calibrate a building energy simulation in EnergyPlus. After validation, the numerical model was used to compare the energy performance of intensive, semi-intensive and extensive green roofs. The three green roof types lead to similar heating energy needs but extensive green roof solution shows higher cooling energy needs than semi-intensive and intensive ones, of 2.8 and 5.9 times more, respectively. Furthermore, the performance of each type of green roof and different insulation properties was compared to traditional roof solutions. With no thermal insulation, extensive green roofs require 20% less energy use than black roofs and show a similar annual behavior than white roofs. Semi-intensive and intensive green roofs energy use is 60–70% and 45–60% lower than black and white roofs, respectively. Well insulated roofs do not take full advantage of evapotranspiration cooling effects, which is particularly noticeable when comparing with high reflective white roofs. [ABSTRACT FROM AUTHOR]

This paper investigates and compares the energetic and ergonomic performance of three different control logics (on–off, PID, fuzzy), used to regulate the emission of the heating system of an energy-efficient building. Tests were carried out on an experimental building, equipped with three electric radiators and a sensor network mapping internal, external and surface thermal conditions. The building–technical system ensemble was evaluated in real time for a monitoring period of five/six days of non-occupancy, winter/midseason weather and Mediterranean climate. All controllers were assessed with regard to thermal comfort and energy consumption in order to return an exhaustive scenario of possible strengths and weaknesses. The comparison showed that fuzzy logic, properly configured, outperformed both PID and on/off controllers reducing energy consumption of 30–70% and maintaining thermal dissatisfaction between comfort limits for all the monitoring period. [ABSTRACT FROM AUTHOR]

Although it is widely acknowledged that occupants play a critical role in building energy consumption, the characteristics of occupants are not well-represented in building simulation. Many statistic and data-mining technologies have been applied to develop a reliable occupant model. In contrast, rather than attempting to develop the occupant model, this study aims to investigate the correlation between the occupant behavior and energy consumption based on a series of experiments. First, this paper discusses the randomness of the occupants’ presence and behavior. The degree of randomness was verified using a Normalized Cumulative Periodogram (NCP) based on a random walk hypothesis. In addition, the correlation between occupant and energy consumption was investigated using the wavelet coherence. This study shows that, while the occupants’ presence has a randomness, it is not strongly correlated to the energy consumption. The occupants’ active action to control a heating/cooling system (turn on/off) is correlated to the energy consumption. In contrast to the occupant's presence, the occupants’ active action does not follow the random walk, and it has no particular frequency. This means that it is difficult to predict the control action of occupants with a specific time interval. [ABSTRACT FROM AUTHOR]

Combined air heating and ventilation systems are often used in low energy buildings. However, operating these systems in the heating mode increases vertical air temperature gradient in rooms and can have negative effect on indoor air quality. The effectiveness of ventilation and personal exposure of the occupants to airborne pollutants generated at the floor level in rooms with the combined air heating and mixing ventilation was analyzed in this paper. The dispersion of pollutants was evaluated under three air distribution methods (in-ceiling four-way and one-way air supply, and high level wall grille air supply) and under three air change rates (1, 2, and 3 ach). Each of these cases were tested at the supply air temperature of +20 °C and +25 °C by performing CFD simulations and experiments in the full-scale test chamber. The results of the experiments showed higher inhaled concentration of the contaminants under the heating mode. The inhaled-to-ambient pollutant concentration ratio varied in the range of 1.05–1.41 under the ventilation mode and it rose up to 1.14–1.78 under combined air heating and ventilation mode. CFD predictions confirmed that pollutants generated at the floor level are entrained into convective boundary layer of the occupant in cases when vertical air temperature gradient was present. The personal exposure to pollutants released at the floor level can increase significantly when a HVAC system runs in the combined air heating and ventilation mode; this effect will not necessarily dissolve with the increase of the air change rate. [ABSTRACT FROM AUTHOR]

The intensification of the Urban Heat Island effect (UHI) is a problem that involves several fields, and new adequate solutions are required to mitigate its amplitude. The construction sector is strictly related with this phenomenon; in particular, roofs are the envelope components subject to the highest solar irradiance, hence any mitigation strategy should start from them and involve their appropriate design process. For this purpose, cool materials, i.e. materials which are able to reflect a large amount of solar radiation and avoid overheating of building surfaces have been deeply analyzed in the last years both at building and urban scales, showing their benefits especially in hot climates. However, green roofs also represent a possible way to cope with UHI, even if their design is not straightforward and requires taking into account many variables, strictly related with the local climatic conditions. In this context, the present paper proposes a comparison between cool roofs and green roofs for several Italian cities that are representative of different climatic conditions. In search of the most effective solution, the answers may be different depending on the perspective that leads the comparison, i.e. the need to reduce the energy consumption in buildings or the desire to minimize the contribution of the UHI effect. [ABSTRACT FROM AUTHOR]

In buildings, HVAC systems consume a high amount of energy to provide thermal comfort for occupants. A methodology is presented in this paper to control thermostat operation of the buildings considering the effects of indoor and outdoor boundary conditions and phase change material (PCM) characteristics. EnergyPlus v8.1 building energy simulation software was used to analyze the energy performance of the PCM incorporated building models and to implement Fanger model to control HVAC thermostat operation according to BS EN 15251:2007 thermal comfort categories. Three types of building HVAC schedule, PCM with different melting points and layer thicknesses were studied for Madrid climate zone. Moreover, the impact of occupants clothing on the energy consumption was investigated. Furthermore, payback analysis was conducted to find out the economic benefits of PCM integration into the building envelopes. Application of PCM improved the cooling and heating energy performances except for the office model in winter (heating period). Additionally, higher energy savings and lower payback periods were observed when PCM with higher melting point was applied to the buildings. Eventually, energy savings in PCM incorporated models were found to improve further when occupants changed their clothing behavior in winter. [ABSTRACT FROM AUTHOR]

This paper presents a cooperative fuzzy model predictive control (CFMPC) for heating and cooling of buildings. Because of different supply zones, the large time constants and the non-linear building dynamics with respect to the different seasons, a CFMPC concept is proposed. The overall non-linear building is split into different zones, which are consisting of input-coupled Takagi-Sugeno (TS)-fuzzy models. Each such TS-fuzzy model is constituted by a local linear model network (LLMN). The LLMN consists of local linear models (LLM), which are representing the different seasons: winter, transition season (fall and spring), and summer. The control of each LLM is realized by model predictive control (MPC). For each building zone the associated MPCs are output-blended by the fuzzy membership functions, which leads to fuzzy model predictive control (FMPC). In addition to the FMPCs a global MPC is controlling the thermally activated building systems, which affect all other zones. To coordinate the different controllers a cooperative iteration-loop is assumed, which leads to cooperative fuzzy model predictive control (CFMPC). The concept is developed for a specific demonstration building and can be easily adapted for other complex buildings. A simulation example demonstrates that the proposed CFMPC achieves a performance increase with less energy consumption, as compared to FMPC controllers and historical measured data of the demonstration building. [ABSTRACT FROM AUTHOR]

Heating, ventilating, and air-conditioning (HVAC) systems consume almost half of the total energy consumption in buildings. In order to reduce the energy consumption of HVAC systems in buildings, different passive heating and cooling strategies and thermal energy storage systems have been adopted. Water wall is an excellent short-term thermal energy storage system which can be used to maintain thermal comfort in buildings while reducing the heating and/or cooling load of the buildings. A significant amount of research work on water wall has been carried out since the 1980s. This paper presents a comprehensive review of the previous studies of water wall systems, focussing mainly on the performance of various configurations of water wall systems and the different research approaches adopted in the literature. The advantages and disadvantages of the different research approaches have been highlighted. It is revealed that the existing water wall research has been based mainly on an energy balance model and experimental modelling, but CFD (computational fluid dynamics) modelling has attracted little attention. Moreover, this review has identified several gaps in the water wall research for further attention. [ABSTRACT FROM AUTHOR]

Energy signatures for air conditioning systems can have characteristics which are not seen with heating systems. This paper explains and illustrates some of the characteristics that are specific to air conditioning systems and describes how energy signatures that take account of them can be applied to produce benchmarks, control charts and diagnostic information. It focusses on the use of energy signatures derived from measured daily system energy consumption. Daily energy signatures can generate more robust energy consumption benchmarks and provide additional insight into unusual energy demand patterns compared to monthly or weekly signatures, albeit requiring slightly more data. In particular, they distinguish between weekday and weekend consumptions. They can be used to generate benchmarks based on standardised annual consumption or standardised annual load factor. In addition they can be used to generate control charts to identify days of unusual consumption for individual systems. More sets of daily energy consumption data are needed to evaluate their diagnostic power. [ABSTRACT FROM AUTHOR]

Ground source heat pump systems have been proved to be one of the most efficient systems for heating and cooling in buildings. However, an optimal energy performance depends on a good control of the auxiliaries, which stand for an important part of the total energy consumption. The authors previously developed an experimental in situ optimization methodology for the water circulation pumps frequency of ground source heat pump systems when single stage and multi-stage ON/OFF regulation is employed. However, the user comfort was not completely met under extreme weather conditions during summer. This paper presents the upgrading of this energy optimization strategy combining circulation pumps frequency variation and building supply temperature compensation in order to ensure the user comfort while keeping high energy savings. Experimental results show that the user comfort is met by means of this new methodology and the energy savings (33%) are even higher than those obtained with the previous methodology. [ABSTRACT FROM AUTHOR]

This paper reports the results of three innovative laboratory tests implemented during winter 2013 in the framework of the Climate for Culture European Project (2009–2014). Thermal analysis was used to assess the heating efficiency of some heaters with different power consumption, geometric shape and dimensions. Experimental laboratory results were obtained under natural indoor environmental conditions and the outcomes were applied to a real case study of two churches on the Italian Alps during the Friendly Heating project. Results provide useful information to help final users and/or conservators to exploit at the best the heating efficiency of some heaters on the basis of the geometric characteristics of the elements and represent helpful advices for their installation, considering both the optimal position for the maximum comfort performance and the need for not exceeding specific risk thresholds for artwork preservation. [ABSTRACT FROM AUTHOR]

In order to reduce energy consumption in buildings, a solution using phase change materials (PCMs) as thermal energy storage (TES) is presented. During summer nights, cold is stored and delivered during the day to reduce cooling load, whereas in winter, heat from solar air collector is stored for heating during morning and evening hours. Proposed is a stand-alone unit suitable for offices, which consists of plates filled with paraffin RT22HC. The objective of the paper is to examine the functioning of the suggested TES system on an annual basis and to explore the feasibility of using it for both, cooling and heating. First numerical model is set up, which assumes 2D geometry and evaluates thermal response, calculations are carried out in Fluent. Then validation of simulations with experimental results is established. Finally the feasibility of storage unit on an annual basis is demonstrated. [ABSTRACT FROM AUTHOR]

Phase Change Materials (PCM) technology can be used for thermal storage and peak load shaving. This paper presents the optimization study of a PCM-Air heat exchanger as well as the development of load shifting solutions which take into account the thermal comfort of the occupants and the indoor air quality. The exchanger contains macroencapsumated PCM (paraffin) and is conceived in a way that facilitates its integration in a ventilation system. It is aimed to shift space heating electrical consumption from peak to off-peak period. The study is performed using an experimentally validated numerical model based on the heat balance approach and the apparent heat capacity method. Several parameters were investigated during the optimization processes, including heat exchanger dimensions, PCM quantity and properties, seeking the configuration with the optimal compromise between stored heat and the time needed for the charging/discharging process. The numerical model was coupled to a building simulation model with several control strategies investigating different scenarios over a one- month winter period. The scenarios vary with increasing complexity, first considering load shifting and thermal comfort, then adding the final price of electricity consumption and finally taking into account the indoor air quality. [ABSTRACT FROM AUTHOR]

Energy demand for heating and cooling of buildings can be minimized through usage of thermal energy storage (TES) systems in building materials. TES in microencapsulated phase change materials provides a new solution to thermally regulated energy efficient buildings. This study summarizes the investigations and analysis of microencapsulated PCMs for building applications. Microencapsulated phase change materials (MPCMs) can be incorporated with many materials that are commonly used in building construction. This paper provides overview of various encapsulation techniques, test methods for MPCMs as well as applications of MPCMs in buildings. There are several micro-encapsulation methods by which the microcapsules of a wide range of sizes between 0.05 μm and 5000 μm can be produced. The MPCM incorporated with concrete, mortar, plaster and other materials have a significant potential to increase the thermal capacity of the mixture. Several authors reported testing of building materials with MPCM. Though the increase of thermal capacity with addition of MPCM is significant the decrease of mechanical properties, such as compressive strength, is relatively small. [ABSTRACT FROM AUTHOR]

Phase change materials can be integrated in building walls to reduce heating energy consumption. However, proper design of the composite material requires a lot of complex calculations. In this paper, we present a methodology based on metamodeling in order to properly design phase change material composite solutions. A low-energy house example is chosen to develop our methodology, simulations being carried with TRNSYS. Box–Behnken design of experiments is used for data sampling in order to be able to produce a polynomial metamodel. First, the metamodel allows to have a profound understanding of the parameters influence: melting temperature, thickness, latent heat, density and thermal conductivity. Second, it is possible to extract from the polynomial form the optimal material properties. Third, the metamodel can be used to design or test different material solutions. Based on this methodology, it is possible to build a simple tool that can be used by architects and engineers. [ABSTRACT FROM AUTHOR]

Artificial intelligence techniques have been successfully applied to control dynamic systems looking for an optimal control. Among those techniques, reinforcement learning has been shown as particularly effective at reducing the dimensionality of some real problems and solving control problems by learning from experience. The use of thermal energy storage active systems in the building sector is identified as suitable option to reduce their energy demand for heating and cooling. However, these systems might be expensive and require appropriate control strategies in order to improve the performance of the building. In this paper a ventilated facade with PCM is controlled using a reinforcement learning algorithm. The ventilated facade uses mechanical ventilation during nighttime to solidify the PCM and releases this cold stored to the inner environment during the peak demand period. It is crucial to decide correctly the schedule of charge and discharge process of the PCM according to the weather and indoor conditions. An experimentally validated numerical model is used to test the performance of the control algorithm under different weather conditions. Important improvements on the energy savings due to the use of control strategies were found and supported by the data under the different tested climatic conditions. [ABSTRACT FROM AUTHOR]

The European Performance of Buildings Directive (EPBD) set the regulatory framework for a cost-effective improvement of the existing dwellings in 2002. The transformation of the stock towards higher efficiency is expected to be stimulated by labelling of the dwellings. The certificate itself is required to contain a list of potential cost-effective measures for the dwellings’ thermal retrofit. However, the theoretical heating consumption provided in the certificate is not a good baseline for the calculation of cost effectiveness, as it is based on normalised dwelling conditions. Normalised conditions include a constant occupancy, constant indoor temperature and normalisations of other parameters, which in reality differ in different types of dwellings. The discrepancies between the normalised theoretical and actual heating consumption are also referred to as the performance gap. In this paper, we examined these discrepancies using the example of The Netherlands. Using descriptive statistics and multiple regression, we investigated several parameters thought to have a different effect on actual and theoretical heating energy use – dwelling, household, occupant behaviour, as well as comfort – in order to propose improvements to the current theoretical consumption calculation. Aside from analysing the total sample, the data is regarded separately for overpredicted and underpredicted consumption records. [ABSTRACT FROM AUTHOR]

Passive Houses are buildings which provide comfortable indoor conditions at an extremely low heating and cooling load. The peak daily average heating and cooling loads are typically below 10 W/m 2 and annual useful energy demands are below 15 kW h/(m 2 a). The Passive House standard was originally developed in Germany. In this paper we show by hygro-thermal dynamic simulation that it is possible to realize residential Passive Houses in all of the world's relevant climate zones, represented here by Yekaterinburg, Tokyo, Shanghai, Las Vegas, Abu Dhabi, and Singapore. The window quality, insulation levels, and mechanical services all depend on the climate as well as on the building's shape and orientation. The resulting annual energy demand for space conditioning of the Passive Houses is 75 to 95% lower than that of a traditionally insulated building of the same geometry. In humid climates like Shanghai or Singapore, special attention must be paid to humidity aspects. In climates which are hot and humid all year long, the total useful energy demand for sensible and latent cooling may exceed 70 kW h/(m 2 a) even in a Passive House. Finally, it is shown that the architectural quality is not compromised by the Passive House requirements. [ABSTRACT FROM AUTHOR]

This paper discussed the influence of apartment location on household space heating energy demand per floor area in multi-apartment buildings. According to the actual data, apartment location has a significant impact on space heating consumption per floor area in multi-apartment buildings. Based on average data of each location, a corner unit on the top floor has a space heating consumption per floor area 26.1% higher than a center unit on the middle floor. For multi-apartment buildings, a correction should be made to reflect the effect of apartment location when billing is calculated from space heating consumption instead of floor area. Location correction factors (LCFs) of seven typical cities based on building type and building age were analyzed by calibrated simulation method. The study finds that LCFs for older buildings are smaller than those of younger buildings, varying from 0.8% to 15.3% for seven typical cities. As for different regions, the greater the heating degree day is, the larger the location correction factor (LCF) is, with the deviation among 5.7–14.4%. LCFs can provide a billing-tool to make a fair allocation of heating costs, which may promote the reform of heat metering and billing in China. [ABSTRACT FROM AUTHOR]

This paper evaluates potential energy savings associated with dynamic insulation materials (DIMs) – material assemblies that can change their thermal resistance through a controlled exchange of liquid or gaseous media – in the exterior walls of buildings. In the analysis, a two-step control strategy is considered to modify the R -value of DIMs based on the temperature difference between internal and external wall surfaces. Using a simulation environment capable of modeling DIMs, a comparative analysis is carried out to evaluate the impact of DIMs on the heating and cooling energy end-uses for single-zone residential buildings in three US climates. Several design and operating conditions are considered to assess the performance of DIMs and their potential energy use savings. The results indicated that variable thermal resistance envelope materials (RSI-0.5/RSI-2.5) have the potential to reduce annual cooling energy use in residential buildings on average by 15% and up to 39% for all three US climates and annual heating energy use by 10% on average for mild US climates depending on the window sizes and internal heat gains. [ABSTRACT FROM AUTHOR]

Wireless sensor network (WSN) for building applications has been considered by many HVAC experts as an efficient tool to promote building energy efficiency and indoor thermal comfort. This paper, therefore, proposes a strategy of using WSN to monitor the temperature distribution in a large-scale indoor space, which aims to (i) improve the quality of the measurements transmitted by wireless signals, (ii) identify the temperature distribution pattern of the large-scale space, and (iii) optimize the allocation of supply air rated flow rate to multiple supply air terminals that serve the space according to the identified temperature distribution pattern. The developed strategy is illustrated by applying it to a real WSN test bed, installed in a typical large-scale space in Hong Kong. Results are presented and discussed, which shows that the phenomenon of temperature uneven distribution was commonly existent in a large-scale space and the developed strategy was able to efficiently improve the quality of measurements by WSN and improve the temperature homogeneity in the large-scale space. [ABSTRACT FROM AUTHOR]

Storage tanks are widely used in heat pump driven heating systems. In this application, storage tanks can: reduce the number of times the heat pump compressor starts; adapt the capacity of heat generation to heat demand; which can offer the possibility to use low rate electricity. This last point will assume increasing importance as smart grids become more prevalent. Floss and Dietrich (Optimierte integration von Pufferspeichern in hydraulische Systeme, in: Proceedings of the International Congress e-nova 2008, Pinkafeld, Austria, 2008, pp. 129–136, ISBN 978-3-9500919-8-4) points out that due to different effects such as mixing or heat conduction inside the tank, the supply temperature at the consumer is lower than the outlet temperature of the heat pump. The average (mass flow weighted) of this temperature drop was named drop of mean temperature (DoMT). It varies between 0.2 °C and 10 °C, depending on the hydraulic integration inside the storage tank, and can reduce the efficiency of the system up to 30%. This paper discusses options to reduce the DoMT, thereby raising the efficiency of the heat pump system through an optimized integration of storage tanks, and a variation of the mass flow rate in the hydraulic system. These results are based on theoretical and practical investigations undertaken at the Institute of Building Energy Systems, University of Applied Sciences, Biberach, Germany. [ABSTRACT FROM AUTHOR]

The damper used for the control of airflow in heating, ventilation and air conditioning systems can constructively be adapted to measure the air velocity with its moment characteristic. It is a device that indirectly determines the air velocity by measuring the position of the blades and the air stream moment acting on it. The subject of this paper is energy consumption of the air torque position damper depending on its structure. The aim is to compare the energy consumption of four possible types of dampers with non-cascading blades: with one blade, with two cross-guided blades, with two parallels-guided blades and with two blades, one of which is a measuring blade and the other remains fixed in horizontal position. The case when there is a straight section of a duct both in front of and behind the damper was considered. Adequacy of the existing mathematical model and energy consumption for all four types of dampers was determined experimentally. It was found that the damper with two blades of which one is a measuring blade and other remains fixed in horizontal position had minimal energy consumption. [ABSTRACT FROM AUTHOR]

Although China's heat metering technology has developed rapidly in recent years, the improvement demonstrates an unbalance in different provinces. It is of great significance to outlook application and sustainability of heat metering technology in various regions technically. Taking the sustainability of heat metering technology as research object, the author establishes a sustainable evaluation model in this paper. Factors in the evaluation model are assigned through a main questionnaire and actual application of typical projects. A pecking-order contrast method is adopted to determine weights of factors in the evaluation model, correspondingly sustainable development of heat metering in various locations is assessed. Sustainability scores in three regions (Northeast, Northwest and North China) are obtained via evaluation model. The model owns high accuracy compared with results of heat metering work assessment by the Ministry of Housing and Urban-Rural Development (MOHURD). The heat metering in the three regions score 60, 62 and 75, respectively, implying that the sustainability in the northeast and northwest is unsatisfactory but in north is somehow better. It is suggested that envelope heat insulation should be increased in the northeast region, while policy support and heat metering technology ought to be enhanced in the northwest. [ABSTRACT FROM AUTHOR]

Conventional weather-compensated heating controllers are often configured to deliver more heating than necessary, resulting in energy losses. Furthermore, they cannot take into account future climate conditions, and yield less than optimal thermal comfort. We have developed a non-invasive add-on module for existing heating controllers that implements an adaptive, model-predictive heating control algorithm. This algorithm helps the heating controller deliver a heating energy just sufficient for maintaining thermal comfort, resulting in energy savings. In this paper we report on the energy savings measured on ten buildings equipped with this device. By monitoring the space heating energy during the 2013–2014 heating season, and by periodically alternating between the new controller and the reference controller, we establish the energy signature of all buildings with both controllers. The comparison of the energy signatures yields the relative energy savings achievable with the new controller. These energy savings are positive for all test sites, with a mean of 28 ± 4% (standard error of the mean). [ABSTRACT FROM AUTHOR]

An experimentally validated numerical model is developed to study the effects of seven design and operational parameters on the heating performance of a solar chimney incorporated with phase change material (PCM) in this paper. It is found that when the latent heat increases from 70 to 170 kJ/kg, the melting time is increased by 103% and freezing time is prolonged by 60%. If heat flux is increased by 33%, the melting time is reduced by 36.4%. Increasing thermal conductivity of the insulation material from 0.02 to 0.06 W/m K, the melting time is prolonged by 47.2%. When absorptivity of the absorber is increased from 0.8 to 1.0, the melting time is decreased by 26.3%. When transmissivity of the glass cover is increased by 25%, the melting time is reduced by 26.7%. For the inlet air temperature, when it decreases from 25 to 15 °C, the freezing time is shortened by 39%. The melting time is only reduced by 8% when thermal conductivity of the absorber is increased by 25 times. Therefore, it can be concluded that the first six parameters have more impact on the system's performance while the thermal conductivity of absorber slightly impacts it. [ABSTRACT FROM AUTHOR]

Temperierung refers basically to wall heating through pipes mounted in or on the inside of the walls. In the context of heritage preservation the Temperierung system was mainly developed by the State Office for Non-State Museums in Bavaria for heating and climatization of museums and exhibit buildings. Based on the ongoing research project “Temperierung as a Tool for Preventive Conservation—An Assessment” a close and interdisciplinary collaboration is established between building physicists, conservators and practitioners from 18 selected museums. The paper highlights the different existing Temperierung systems within the project, main components of the system and different types of application. The main principles of the technique are explained and compared to more commonly known heating systems like convector/radiator heating and wall/floor heating. Preliminary results of the measured indoor climate and effects of the Temperierung heating system of several chosen museums are presented. The impacts of the indoor climate to the conservation of artifacts, influenced by Temperierung heating, are discussed with typical methods of indoor climate assessment and with conservational assessment. The detailed and neutral description of Temperierung heating gives a basis for planners and persons in charge for retrofitting historical museum buildings. [ABSTRACT FROM AUTHOR]

Energy performance simulation is a generally used method for assessing the energy consumption of buildings. Simulation tools, though, have shortcomings due to false assumptions made during the design phase of buildings, limited information on the building's envelope and installations and misunderstandings over the role of the occupant's behaviour. This paper presents the results of a Monte Carlo sensitivity analysis on the factors (relating to both the building and occupant behaviour) that affect the annual heating energy consumption and the PMV comfort index. The PMV results are presented only for the winter (heating) period which is important for energy consumption in Northern Europe. The reference building (TU Delft Concept House) was simulated as both a Class-A and a Class F dwelling and with three different heating systems. If behavioural parameters are not taken into account, the most critical parameters affecting heating consumption are the window U value, window g value and wall conductivity. When the uncertainty of the building-related parameters increases, the impact of the wall conductivity on heating consumption increases considerably. The most important finding was that when behavioural parameters like thermostat use and ventilation flow rate are added to the analysis, they dwarf the importance of the building parameters. For the PMV comfort index the most influential parameters were found to be metabolic activity and clothing, while the thermostat had a secondary impact. [ABSTRACT FROM AUTHOR]

The paper presents the results of the analysis of the impact of various ventilation systems on the energy consumption performed for one Polish museum building that was built in 1929–1930. Simulations were carried out with the use of two computer codes: CONTAM and ESP-r. Multi-zone models including the exhibition rooms and the staircase were prepared. The simulations were made of synthetic weather data for one of the Polish towns for two months of the heating season. Twenty-four hour variability of internal heat gains was taken into account. The results show clearly that the natural ventilation system (which is currently used in the building) enables the air exchange with fresh air on the first floor only. The air infiltration on the upper levels is close to zero. Rebuilding the ventilation system generates changes in the energy demand of the building. It is presented how the heat demand increases with the increase of the ventilation air flow and what is the impact of the air infiltration on the heat demand for different variants of ventilation. [ABSTRACT FROM AUTHOR]

To foster the transition to more sustainable energy systems, policymakers have been approving measures to improve energy efficiency as well as promoting smart grids. In this setting, building managers are encouraged to adapt their energy operations to real-time market and weather conditions. Yet, most fail to do so as they rely on conventional building energy management systems (BEMS) that have static temperature set points for heating and cooling equipment. In this paper, we investigate how effective policy measures are at improving building-level energy efficiency compared to a smart BEMS with dynamic temperature set points. To this end, we present an integrated optimisation model mimicking the smart BEMS that combines decisions on heating and cooling systems operations with decisions on energy sourcing. Using data from an Austrian and a Spanish building, we find that the smart BEMS results in greater reduction in energy consumption than a conventional BEMS with policy measures. [ABSTRACT FROM AUTHOR]

Climate change has been shown to significantly alter the heating and cooling needed to maintain thermal comfort within a home. However, limited studies have investigated the impact on the design philosophy associated with achieving an energy efficient building envelope with the onset of climate change. Applying robust future TMY for 2070 the change in heating and cooling demand has been studied in this paper for various combinations of external and internal wall insulation, roof insulation, reflective foil, thermally reflective roofs and different floor coverings. A building thermal model was used for the mild temperate climate of Adelaide, Australia, which requires both heating and cooling, but is dominated by heating. Climate change was found to increase and shift this demand to cooling dominated. It was determined that with climate change, heating becomes significantly less important in better insulated buildings and therefore measures which reduce cooling load are more critical. It is concluded that in this climate zone, climate change design approaches need to dramatically change to focus on cooling, contrary to present strategies. [ABSTRACT FROM AUTHOR]

The accuracy in assigning a climatic zone to a city is essential for studying the correct sizing of domestic hot water, heating, and cooling systems, as well as of construction materials. In Spain, the current system for allocating climate zones is one proposed by the Código Técnico de la Edificación (Technical Building Code) (CTE) and includes a method based on Royal Decree 235/2013, Procedimiento Básico para la Certificación de Eficiencia Energética de Edificios de los Edificios (Basic Procedure for Certification of Energy Efficiency of Buildings), as well as on the recognized document CERMA to calculate energy demands, CO 2 emissions, and energy ratings. The climatic data of cities is not always available, so the CTE method has proposed some solutions, but they are not always precise enough. In this paper, we propose an alternative classification of climatic zones as a result of applying a new method based on approximation and interpolation functions, with a maximum error of 5.773e − 15 in summer and 6.661e − 16 in winter. This new method has been applied and tested in Andalusia in Southern Spain, a region with 772 municipalities. According to the climatic data available, the new proposed method has resulted in more precise climatic zones than the two versions of the CTE (2009 version and the 2013 update). The results are closer to reality, and the method is exportable to any region. [ABSTRACT FROM AUTHOR]

The earth–air heat exchangers (EAHE) are promising technology for passive heating/cooling of buildings. The study carried out to evaluate annual thermal performance of EAHE system for hot and dry climatic conditions of Bhopal (Central India) has been presented in this paper. A quasi-steady state, 3-D model based on computational fluid dynamics (CFD) was developed to evaluate the heating/cooling potential of EAHE system. The simulation results were validated against experimental observations taken on experimental set-up installed in Bhopal (Central India). The energy metrics namely energy payback time (EPBT) and seasonal energy efficiency ratio (SEER) for EAHE system were evaluated on the basis of energy analysis of simulation results. The embodied energy for the EAHE system was evaluated as 1663.88 kW h. The maximum heating potential and cooling potential of EAHE obtained in the months of January and May, respectively, were calculated as 191.06 kW h and 247.25 kW h. The total yearly energy output of EAHE system for air flow velocity of 5 m/s was found as 1290.53 kW h. The EPBT of EAHE system was calculated as 1.29 years. The SEER for typical summer and winter months were calculated as 1.34 and 1.10, respectively. The CO 2 emission mitigation potential and the total carbon credits earned from EAHE system were calculated as 101.30 tonnes and Rs 1, 72,817.80 ($2837.60), respectively by considering its life span as 50 years. [ABSTRACT FROM AUTHOR]

The paper presents the results of 1-year measurement of indoor environment parameters (temperature, relative humidity, CO 2 concentration) in exhibition rooms of one Polish museum in various periods of the year, and the results of simulation on thermal model of this building. The influence of a temperature control scheme in museum rooms on heating and cooling demand was analysed. The actual state (poor control of internal temperature) and ideal control of internal temperature were analysed – two cases in the winter and two cases in the summer. Simulations were performed by ESP-r program. The multi-zone model of the building was validated based on measurement data. Measurements and simulations revealed significant variations in the temperature in the rooms of the museum. The analysis showed that the maintaining internal temperature at constant level of 20 °C in winter reduces monthly heat demand in most of the exhibition rooms. Obtained effect is 5–16% depending on the premises. Provision the raise of a temperature by 1 K results in the increase of heat consumption by 6%. Maintenance of a desired internal temperature, which does not exceed 24 °C in the summer, requires the provision of coolness to the museum premises. [ABSTRACT FROM AUTHOR]

The Chinese Kang, a traditional heating device, is widely used in northern rural China. It recovers the heat from cooking smoke and provides local thermal comfort to people sitting or lying on it. However the heat supply ability of the traditional Kang is limited due to constraints of the surface temperatures and heat transfer coefficients. In this paper, a new Chinese Kang with forced convection (CKFC), which adopted hot water as the heat transfer medium and added a small fan to enhance convective heat transfer, was developed. A full-scale CKFC system was constructed for actual application in a rural house and its thermal performance was measured. Experimental data show that during the space heating period, the heating power of forced air convection ranged from 625 W to 1170 W, while that through the CKFC surfaces was only 200–500 W in the local heating or space heating mode to maintain local thermal comfort. Meanwhile, the CKFC retained the merits of a traditional Kang by providing local thermal comfort. The measured asymmetry of Kang plate surface temperatures was 6.7 °C. Overall, the CKFC has satisfactory performances as a new heating terminal device in rural houses. [ABSTRACT FROM AUTHOR]

Following the electric load (FE) and following the thermal load (FT) strategies both have advantages and disadvantages for combined cooling, heating and power (CCHP) systems. In this paper, the performance of different strategies is evaluated under operation cost (OC), carbon dioxide emission (CDE) and exergy efficiency (EE). Analysis of different loads in one hour is conducted under the assumption that the additional electricity is not allowed to be sold back to the grid. The results show that FE produces less OC, less CDE, and FT produces higher EE when the electric load is larger. However, FE produces less OC, less CDE and higher EE when the thermal load is larger. Based on a hybrid electric–thermal load (HET) strategy, compromised electric–thermal (CET) strategies are innovatively proposed using the efficacy coefficient method. Additional, the CCHP system of a hotel in Tianjin is analyzed for all of the strategies. The results for an entire year indicate the first CET strategy is the optimal one when dealing with OC, CDE and EE. And the second CET is the optimal one when dealing with OC and EE. Moreover, the laws are strictly correct for different buildings in qualitative terms. [ABSTRACT FROM AUTHOR]

The paper examines implementation of heat saving measures in buildings in 2050, under the assumption that heat and power supply comes solely from renewable resources in Denmark. Balmorel – a linear optimisation model of heat and power sectors in Denmark is used for investigating economically viable levels of heat savings, which can be implemented by reducing heat transmission losses through building elements and by installing ventilation systems with heat recovery, in different future Danish heat and power system scenarios. Today almost 50% of heat demand in Denmark is covered by district heating. A further expansion of district heating network in Denmark is assessed and penetration of heat savings is analysed in this context. If all heat saving measures, included in the model, are implemented, heat demand in Danish buildings in 2050 could be reduced by around 40%. Results show that it is cost effective to reduce from approximately 12% to 17% of future heat demand in buildings depending on assumed lifetime and costs of heat saving measures. Individual heating areas have higher penetration of heat savings than district heating areas. When district heating systems are expanded, an overall penetration of heat savings slightly decreases along with lower capacity investments and system costs. [ABSTRACT FROM AUTHOR]

For military and disaster relief housing, rapidly deployable shelters must be lightweight, be packaged in a small volume for transportability, and be erected without heavy lifting equipment. A critical design criterion is also energy efficiency in heating and cooling. To meet these priorities, the research team has utilized origami as inspiration for a thermally insulated rigid wall deployable shelter that can be erected manually through counterweighting. To enhance energy efficiency, improvements in the shape of a structure (i.e., member lengths and angles) at a design stage can lead to savings throughout its lifecycle. This is magnified in the context of mass-production of deployable shelters, where any improvements are multiplied. Structural efficiency is also critical to achieve lightweight design. This paper presents a multi-objective shape optimization methodology which balances the priorities of structural performance (i.e., minimum deflections) and energy efficiency (i.e., minimum thermal energy load). This is demonstrated for the case study of a deployable shelter. Design variables include geometric parameters. Constraints relate to the package size and capability of interfacing with existing technologies. Structural analysis is performed using a parametric finite element program. Thermal energy is calculated using EnergyPlus. An optimized solution is found and compared against existing military solutions. [ABSTRACT FROM AUTHOR]

The coefficient of performance (COP) of air-source heat pumps (ASHP) decreases toward low outdoor temperatures. This paper presents an auto-cascade heat pump system (ACHPS) with the objective to improve the heating performance of ASHP in cold climate. The auto-cascade process is achieved based on the separation of binary zeotropic refrigerant mixture consisting of pure refrigerants with different boiling points. Fluid selection for the ACHPS is carried out to validate the feasibility for potential application. Based on the performance analysis on COP, 15 qualified binary mixtures are obtained. R143a/R600 (0.8/0.2) tops the potential working fluid with a COP of 2.15. The effects of system parameters, such as circulation composition, heat transfer fluid (HTF) temperature glide and temperatures of heat source and sink on COP and exergy efficiency of ACHPS are thereafter investigated. The simulation results show that there exist a maximum COP of 2.15 and a maximum of exergy efficiency of 37.2% at the R143a mass fraction of 0.8 when the ambient temperature and heating temperature are −10 °C and 50 °C, respectively. Finally, by comparison with the single-stage heat pump operating with commercially available refrigerants, the proposed ACHPS shows an advantage of compressor isentropic efficiency. The compression isentropic efficiency of ACHPS could be increased by 25.5% compared to the single stage cycle working with R407c when the ambient temperature is −10 °C. [ABSTRACT FROM AUTHOR]

Being increasingly insulated, new buildings are more and more sensitive to variations of solar and internal gains. Due to an important use of electrical heating systems, especially in housing, France is facing a growing problem of peak load on its electricity grid. Controlling the heating system often constitutes an efficient solution to shift heating loads while maintaining indoor comfort. The proposed energy management is a predictive set of optimal commands issued from a dynamic programming optimization knowing in advance the weather, occupancy and internal gains for the next 7 days. This method is tested on a low energy house situated in France with an annual heating demand of 14 kWh/m 2 . In this paper, load shifting according to utility rate incentives and carbon emissions are studied. The importance of building models as well as envelope insulation and thermal mass on energy management results is shown. [ABSTRACT FROM AUTHOR]

Several studies have shown that the actual energy performance of buildings can differ significantly from its designed value. An important part of this performance is constituted by the building fabric's thermal performance. A common method to evaluate the latter for an actual building is the co-heating test. The co-heating test comprises a quasi-stationary heating experiment followed by linear regression analysis of aggregated building performance data. This paper reviews related research work and cristallises the current state-of-the-art. The physical phenomena working behind the scenes of the generally assumed simplified heat balance are discussed. Statistical constraints generally prevent these from being uncovered fully during the analysis. Multiple linear regression is proposed as the most sensible method to analyse co-heating measurement data. A novel way to visualise such analysis, deduce building performance data graphically and compare different co-heating test results is presented. [ABSTRACT FROM AUTHOR]

This paper proposes a new method for an optimal control of the heating system at the building scale. This control is a new approach of energy planning that aims to decrease the heating consumption/expenses over a defined prediction horizon while respecting the occupants’ thermal comfort. It employs a simplified building thermal model to simulate the building thermal behavior taking into consideration the weather predictions. This approach is based on the application of Monte Carlo method, i.e., a random generator for the heating system scenarios. The aim is to determine the optimal heating plan for the prediction horizon that fulfills the constraints regarding the thermal comfort of occupants and the minimization of the energy consumption/expenses together with achieving a load shedding. [ABSTRACT FROM AUTHOR]

• Freely available online overview of district heating efficiency indicators. • Hourly district heating energy use data from approx. 43 000 buildings. • Building stock segmented into building typologies for analysis of: • -1) Heating energy use intensity, 2) load variation and 3) cooling efficiency This paper provides a state-of-the-art and freely available online overview of the district heating (DH) efficiency of Danish building typologies. The overview is based on DH consumption data from 42 969 buildings constructed up until 2017 that in combination with data from the Danish Building and Dwelling Register constitutes a dataset with a previously unseen level of detail, confidence, sample size, and research opportunities. The paper also presents an initial analysis of the dataset in terms of three heating efficiency indicators, namely 1) Annual heating energy use intensity, 2) Daily heat load variation, and 3) Cooling efficiency. The overall finding was that building typologies perform significantly different from one another concerning indicators 1 and 2, but not for indicator 3. It is therefore not possible to declare one building typology more efficient than the other as this depends on the building construction year and the considered efficiency indicator. The data indicate that further energy-efficiency improvements of the existing building stock are essential to the realization of 4th Generation District Heating technologies in Denmark and that these improvements most likely will lead to increased heat load variations that need to be addressed, for instance by enabling a larger degree of demand-side flexibility in the existing district heating systems. The large temporal variation of the buildings' cooling efficiency indicates that there is a potential for rethinking e.g. domestic hot water production in the summer or introduce differentiated billing based on the daily, weekly, or maybe seasonal cooling performance. The presented dataset can be subject to several future investigations which are also discussed in the paper. [ABSTRACT FROM AUTHOR]

Future district heating systems (DHS) will be supplied by renewable sources, most of which are limited in temperature and flow rate. Therefore, operational optimization of DHS is required to maximize the use of renewable sources and minimize (fossil) peak loads. In this paper, we present a robust and fast model-predictive control approach to use the thermal mass of buildings as a daily storage without violating temperature constraints. The novelty of this paper includes two elements. First, the focus on an operational control strategy that explicitly accounts for temperature-limited renewable sources, like a geothermal source. Secondly, the optimization problem is formulated as a (nearly) convex optimization problem, which is required for adoption of model-predictive control in practice. The examples show that the peak heating demand can be reduced by 50%, if the thermal inertia of the buildings is used and the heating setpoints are adapted. Furthermore, the operational optimization finds the proper balance between benefits of pre-heating using renewable sources with limited capacity and costs of additional heat losses due to pre-heating. [ABSTRACT FROM AUTHOR]

• A new enclosed melting system was built for deicing the bottom of a train. • A new method was used for simulating gravity shedding melting in complex models. • The effect of supply air properties on system performance was studied. In winter, a large amount of icing and snowing occurs in outdoor equipment and systems, which adversely affects their lifespan. The melting process is divided into two parts: convection melting and gravity shedding melting. This paper is based on an experiment with a real high-speed train unit, and it establishes a three-dimensional computational fluid dynamics model of the bogie area to validate the mathematical model of the winter ice melting experiment. A numerical simulation was used to calculate the airflow in the baffle-enclosed space and to predict the effects of interactions between air and the ice body on heat transfer and phase change. The influence of air velocity and temperature on the heat transfer was analyzed. The computational simulation effectively quantifies the amount of heat transfer and energy consumption under different conditions. This paper also presents a research method for the simulation of gravity shedding in complex models. These models provide information for the construction of similar ice melting models. This paper has suggested that for thin ice bodies, convection melting was the dominant strategy. For thick ice bodies, however, gravity shedding melting became dominant. The study also confirmed that enclosed hot-air ice-melting systems gave a better energy performance than unenclosed systems. [ABSTRACT FROM AUTHOR]

• Moisture needed to be removed in three building types is calculated. • Salt supported porous composites satisfy most climates and building types. • Zeolites are suitable for return air state, ARI summer and ARI humid climates. • Polyelectrolytes can cope with humid climates and buildings with high wet load. Energy conservation and emission reduction have become a global consensus. As a novel promising energy-saving dehumidification technology, desiccant coated heat exchanger (DCHE)-based air conditioning systems have attracted immense attention recently. This paper provides a quick and reasonable selection of desiccant materials for DCHE systems using water as the cooling medium in different buildings and climates. By the theoretical calculation of moisture needed to be removed in three types of buildings (offices, residential buildings and restaurants) and the analysis of the dehumidification capacity of desiccants in DCHEs reported in the literature, optimal desiccants for different building types and ambient air conditions under given parameters are recommended. Salt-supported porous composite desiccants possess flexible dehumidification performance and can be utilized in most climates and building types, except for extremely humid indoor environments with high requirement for fresh air. Zeolites are especially suitable for return air states, American Air-Conditioning and Refrigeration Institute (ARI) summer and ARI humid climates in buildings with moderate indoor moisture gain, such as offices or residential buildings. Polyelectrolytes can be applied in humid climates and buildings with high indoor wet loads, such as restaurants. This paper offers a promising route to the applications of desiccant materials in novel energy-saving air conditioning technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • In the US, carbon savings are readily achievable by transitioning to heat pump technologies for the vast majority of homes. • The heat pump performance required to achieve carbon and cost neutrality varies by a factor of four across the US. • Energy cost neutrality is much harder to achieve than carbon neutrality. • Achieving carbon and energy costs savings is much easier when replacing older, low efficiency equipment. In order to meet climate goals, it will be necessary to significantly reduce the greenhouse gases emitted by homes. A key factor in the US is to reduce the on-site combustion of fossil fuels for heating end-uses and to replace this with use of electric heat pump technologies connected to a low-carbon grid. The replacement of natural gas furnaces with electric heat pumps is a key home decarbonization strategy. However, the potential for space heating electrification to reduce greenhouse gas emissions depends on the carbon dioxide equivalent (CO 2 e) content of the electricity used by the heat pump. This varies considerably depending on the source of electricity, with large state to state variability. Furthermore, household energy costs are likely to be impacted by the electrification of space heating, because retail energy prices for both natural gas and electricity in each state vary by factors of seven and four, respectively. Contractors, energy programs, government and building code officials, as well as consumers need clear indications of the likely CO 2 e and energy cost impacts of proposed electrification projects, because these will affect decarbonization choices and rationales around scaled heating electrification. Government and utility programs also need to be aware of the likely outcomes of any supported/incentivized measures. In this paper, we investigate these effects by looking at new metrics to analyze the change in CO 2 e emitted and the cost to meet home heating loads when switching from a natural gas furnace to a heat pump for the contiguous 48 states of the mainland US. [ABSTRACT FROM AUTHOR]

• Occupants on-demand heating control behavior in a rural residential building is investigated. • Independently controlled split-type heating equipment were used to elucidate actual demand patterns. • Data collection over three years under an interference avoidance scheme. • Five representative intermittent heating patterns were obtained from a real-world case study. A better understanding of actual heating demands is crucial for optimizing operational heating systems, because disparities between expected load and actual demand are key factors in inefficient heating system design, implementation, and corresponding energy loss. Additionally, the discrete, energy consumption-based billing systems applied to freestanding rural residential buildings encourages reductions in energy waste but produces spatially and temporally distinct heating patterns. Conventional heating systems have only basic controls and slow response times that cannot reflect actual user demand. Hence, this paper presents an experimental scheme for measuring room-wise heating demands, and thus, the actual heating demand patterns of rural residential buildings. A case study was conducted on a typical rural residential building in Beijing to validate the method's feasibility. Real-world usage patterns were obtained using indoor environment sensors and independently-controlled heating devices that collected the operational parameters of each room over three years, in a long-term non-intervention study design. Clustering analysis and various indicators were used to characterize heating demand for each room: heating patterns, usage intensity, and temporal variation. In most case, the occupants heated only a few rooms, rather than the whole building. These results have potential real-word implications for predicting occupant heating behavior and energy conservation. [ABSTRACT FROM AUTHOR]