Thermo-active Building Systems Research Articles

On Slowing Climate Change with Ecological, Thermo-Active Building Systems

In the early days of energy conservation(1980s) several countries took the need for energy efficiency seriously enough to sponsor some demonstration buildings. For instance, a US university design concept was built in Regina, Canada in1978. The Saskatchewan Energy Conservation house [1s]demonstrated a new, passive technology. It had super-insulated and airtight walls, large windows on the south facade, evacuated solar pipes for domestic water heating, and a heat recovery ventilator. Despite of all the technology demonstrated there, as Bomberg et al [2] explains, the passive measures were not accepted in the Canadian marketplace because the builders modified the heating system and thereby changed the air flow pattern in the house. The 1995, German passive house was accepted in marketplace because the built system could be duplicated as it was demonstrated. In this case, saving from the elimination of expensive boiler were used to improve the level of thermal insulation and air tightness. These developments led to acceptance of a few points from building science [2-4], namely: (1) any building is a system, (2) a design team should work together starting with the conceptual stage, (3) heat, air, and moisture flows are not separable, and their interactions must be recognized, (4) excellent air tightness and a high-level of thermal insulation are required in all climates.

TABSOLARⓇ – a novel approach of thermo-active (solar) building systems based on ultra-high performance concrete (UHPC)

• The novel TABSOLAR® elements with bionic channel structure based on ultra-high performance concrete (UHPC) offer new possibilities to use façades as (solar) thermal source for direct usage or as a low-temperature source for heat pumps and can be used as thermo-active building components inside for heating or cooling. • TABSOLAR® elements are produced directly from UHPC by an innovative membrane vacuum deep-drawing process. TABSOLAR® elements are novel (solar) thermal components made from ultra-high performance concrete (UHPC) which can be used as designable glazed or unglazed façade cladding elements or thermo-active building systems for heating and/or cooling. They are produced with an innovative production technology which is developed in a current research project together with appropriate system concepts. In order to simplify the system design process and visualize possible TABSOLAR® façades on site, new software tools are being developed. Finally, a demonstration façade will be installed on a renovated two-family residential building. The ongoing interactive design process of this first use case is an important part of the project and the overall TABSOLAR® concept.

Model Predictive Control-based Surface Condensation Prevention for Thermo-active Building Systems (TABS): In Regard to the Partial Theoretical Model Approach

Model Predictive Control-based Surface Condensation Prevention for Thermo-active Building Systems (TABS): In Regard to the Partial Theoretical Model Approach

Elements of energy infrastructure modernization of buildings and cities

The formation of effective energy technological systems of buildings and cities in new economic conditions requires comprehensive analysis of dynamic of their developing, complex of diverse conditions of their function, diverse factors of their changes. The need for a systematic approach to the analysis of the functioning of complex technical systems is difficult to dispute. Methodologically, the task is to select from the many approaches the most appropriate for achieving the assigned engineering tasks. This implies the need for a comprehensive analysis of the subject area of the studied systems and the choice of the necessary system equipment, commensurate with the complexity of the selected objects. This article presents a number of elements and technologies for the modernization of the infrastructure of buildings and cities, which in practice shows their energy efficiency: fuel cells, recuperators, heat pumps, thermoactive building systems, and a predictive management with using of weather data - an intelligent tool for controlling the building’s air conditioning.

Countercurrent Heat Exchange Building Envelope Using Ceramic Components

Research and development in building envelope design have promoted the convergence of two system types, Thermo-Active Building Systems and Adaptive Building Envelopes, that re- conceptualize the envelope as a distributed energy transfer function that captures, transforms, stores, and even re-distributes energy resources. The widespread deployment of Thermo-Active Building Systems as a building envelope will depend on several factors. These factors include the value of the design attributes that impact energy transfer in relation to the performance of the building envelope assembly and the return on investment that these attributes individually or in the aggregate can provide as a reduction in Energy Use Intensity. The research focus is on the design development, testing, and energy reduction potential of a Thermo-Active Building System as an adaptive countercurrent energy exchange envelope system using ceramic components: the Thermal Adaptive Ceramic Envelope.

Framework for model predictive control (MPC)-based surface condensation prevention for thermo-active building systems (TABS)

The potential risk of developing surface condensation keeps thermo-active building systems (TABS) from being applied in buildings located in partly warm and humid climate regions. This study presents a framework for model predictive control (MPC)-based surface condensation prevention that can avoid the surface condensation during the cooling periods when the TABS is in operation. Because MPC determines the input signal for the system not only on the basis of the current states but also on the impact that the actions will have on the future states, it is suitable for anticipatory surface condensation control that must respond to both dynamic indoor condition changes and the time-delay in hygrothermal transfer in advance. Heat and moisture transfer dynamic models were developed for prediction of future states and these dynamic models were calibrated with the measured data to improve the surface condensation prediction accuracy. On the basis of future states predicted by the calibrated dynamic models, the MPC-based condensation prevention framework adjusts the surface temperature for the TABS in ways that ensure indoor thermal comfort and energy efficiency without the development of surface condensation. The results demonstrated that the MPC-based TABS operation achieved 21.0 − 29.6% site cooling distribution energy savings compared to the conventional forced air-based cooling mode depending on the climatic regions; in comparison between the TABS governed by the MPC framework and by the on/off control, 2.5 − 10.0% more site cooling distribution energy savings were achieved through use of the MPC framework than through use of the on/off control.

Countercurrent Heat Exchange Building Envelope Using Ceramic Components

Research and development in building envelope design have promoted the convergence of two system types, Thermo-Active Building Systems and Adaptive Building Envelopes, that re- conceptualize the envelope as a distributed energy transfer function that captures, transforms, stores, and even re-distributes energy resources. The widespread deployment of Thermo-Active Building Systems as a building envelope will depend on several factors. These factors include the value of the design attributes that impact energy transfer in relation to the performance of the building envelope assembly and the return on investment that these attributes individually or in the aggregate can provide as a reduction in Energy Use Intensity. The research focus is on the design development, testing, and energy reduction potential of a Thermo-Active Building System as an adaptive countercurrent energy exchange envelope system using ceramic components: the Thermal Adaptive Ceramic Envelope.

Evaluation of Thermal Behavior of the Skeleton in a Green Building with the Aid of TABS

In this study, an office building in Japan that incorporates energy-saving features and environmental technologies was investigated. This office building features a green façade, natural ventilation, a concrete slab with no suspended ceilings, and thermo-active building systems. Two airconditioning systems were installed in this building—a ceiling radiation air-conditioning system and a whole floor-blow off air conditioning system. In addition, a natural ventilation system was installed. We surveyed the heat flux of the ceiling surface and indoor thermal environment of this building from 2015 through 2016. The ceiling using the heat storage amount of concrete maintains a constant temperature in the workplace during as well as after office hours. We also performed detailed measurements of the heat flux of the ceiling surface and indoor thermal environment in the summer of 2017. The results showed that the ceiling radiation air-conditioning system provided a stable thermal environment. Furthermore, we report that making use of the thermal behavior of the skeleton improved the operation of the ceiling radiation airconditioning system.

オフィスにおける躯体蓄熱型放射空調システムの基本性能の検証 冷温水配管の設置位置による冷房能力・応答特性の比較

オフィスにおける躯体蓄熱型放射空調システムの基本性能の検証 冷温水配管の設置位置による冷房能力・応答特性の比較

Thermo-active building systems and sound absorbers: Thermal comfort under real operation conditions

Radiant systems are established today and have a high ecological potential in buildings while ensuring thermal comfort. Free-hanging sound absorbers are commonly used for room acoustic control, but can reduce the heat exchange when suspended under an active slab. The aim of this study is to evaluate the impact on thermal comfort of horizontal and vertical free-hanging porous sound absorbers placed in rooms of a building cooled by Thermo-Active Building System (TABS), under real operation conditions. A design comparing five different ceiling coverage ratios and two room types has been implemented during three measurement periods. A clear correlation between increase of ceiling coverage ratio and reduction of thermal comfort could not be derived systematically for each measurement period and room type, contrarily to what was expected from literature. In the first two monitoring periods in the larger office rooms, rooms with higher coverage ratios reported higher operative temperatures. This correlation was however not clear from the monitoring in the smaller offices and other measurement periods. In all monitored rooms, a strong influence of the user behaviour on thermal comfort has been observed. A higher temporal offset between ceiling and operative temperature was also observed in rooms equipped with absorbers.

Savings through the use of adaptive predictive control of thermo-active building systems (TABS): A case study

The building sector is one of the main consumers of energy. Therefore, heating and cooling concepts for renewable energy sources become increasingly important. For this purpose, low-temperature systems such as thermo-active building systems (TABS) are particularly suitable. This paper presents results of the use of a novel adaptive and predictive computation method, based on multiple linear regression (AMLR) for the control of TABS in a passive seminar building. Detailed comparisons are shown between the standard TABS and AMLR strategies over a period of nine months each. In addition to the reduction of thermal energy use by approx. 26% and a significant reduction of the TABS pump operation time, this paper focuses on investment savings in a passive seminar building through the use of the AMLR strategy. This includes the reduction of peak power of the chilled beams (auxiliary system) as well as a simplification of the TABS hydronic circuit and the saving of an external temperature sensor. The AMLR proves its practicality by learning from the historical building operation, by dealing with forecasting errors and it is easy to integrate into a building automation system.

Adaptive predictive control of thermo-active building systems (TABS) based on a multiple regression algorithm: First practical test

There is a growing trend for the use of thermo-active building systems (TABS) for the heating and cooling of buildings, because these systems are known to be very economical and efficient. However, their control is complicated due to the large thermal inertia, and their parameterization is time-consuming. With conventional TABS-control strategies, the required thermal comfort in buildings can often not be maintained, particularly if the internal heat sources are suddenly changed. This paper shows measurement results and evaluations of the operation of a novel adaptive and predictive calculation method, based on a multiple linear regression (AMLR) for the control of TABS. The measurement results are compared with the standard TABS strategy. The results show that the electrical pump energy could be reduced by more than 86%. Including the weather adjustment, it could be demonstrated that thermal energy savings of over 41% could be reached. In addition, the thermal comfort could be improved due to the possibility to specify mean room set-point temperatures. With the AMLR, comfort category I of the comfort norms ISO 7730 and DIN EN 15251 are observed in about 95% of occasions. With the standard TABS strategy, only about 24% are within category I.

Case-study of Thermo Active Building Systems in Japanese Climate

Thermo active building systems (TABS) have been applied in office buildings as a promising energy efficient solution in many European countries. The utilization of building thermal mass helps to provide high quality thermal environments with less energy consumption. However, the concept of TABS is entirely new in Japan. This paper introduces and evaluates TABS under Tokyo weather conditions to clarify the potential of use TABS in Japan. Cooling capacity of thermo active building systems used in an office building was evaluated by means of dynamic simulations. Two central rooms of the office were selected for the analysis. Six water control strategies were studied and two of those were found reasonable and suitable for TABS use in Tokyo. These two strategies are: free-cooling using underground heat exchanger combined with TABS and free-cooling with desiccant dehumidification system. For these two cases, the operative temperature was between 22-27°C during 97∼99% of the occupation time. The operative temperature drift was less than 4°C per day. The pump running time was 7hours per day and the cooling power of the TABS was 36W/m2 floor area. For those free-cooling cases, the average supply water temperature was 20°C, which shows that free-cooling is achievable using underground heat exchangers even considering the temperature increase of the ground during cooling season.

Adaptive predictive control of thermo-active building systems (TABS) based on a multiple regression algorithm

There is a growing trend toward the use of thermo-active building systems (TABS) for heating and cooling buildings, since these systems are known to be very economical and efficient. However, due to the large thermal inertia, the control of these systems turns out to be complicated and time-consuming in the parameterization. With standard control strategies, the required thermal comfort in buildings often cannot be met, especially if the internal heat sources are suddenly changed. This paper presents a novel adaptive and predictive computation method, based on multiple linear regression (AMLR) for the control of TABS. Through the self-learning effect, no parameterization of heating and cooling curves is necessary. The algorithm is compared to a conventional control strategy for TABS. In this simulation case, it turns out that the adaptive and predictive control strategy can achieve a saving of pump-running time of up to 81% while increasing thermal comfort. In addition, the algorithm is validated by a three-week laboratory experiment. With simple calculation approaches, this algorithm proves to be very practical and can easily be integrated into a building's automation system. Furthermore, it offers the possibility for load shifts from the use of the thermal mass of a building.

Mechanical behaviour of thermally activated building structures

This paper focuses on two low-energy systems – thermo-active building systems and energy foundations – both of which use concrete elements that are already required for structural reasons but which simultaneously work as heat exchangers. The aim of this work was to study the mechanical behaviour of these concrete elements due to the inclusion of polyethylene pipe heat exchangers cast directly into the concrete core and the influence of fluids flowing inside at a moderate temperature. Cylindrical and cubic specimens of two types of concrete (H-25 and H-30) were manufactured in order to study the influence of temperature through compression and pull-out tests and the influence of the embedded pipes in different positions using compression tests. The mechanical properties were found to decrease with an increase in temperature in both concrete types, with a sharper decline in the H-30 specimens. The pipe layout reduced the mechanical resistance of the structural elements regardless of the type of concrete used, with the most damaging position being perpendicular to the load. It is concluded that thermo-active reinforced concrete elements perform best when the polyethylene pipes are placed parallel to the load and the temperature of fluid in the pipes is lower than 70°C.

An experimental study of natural and mixed convection over cooled vertical room wall

Energy demands for cooling of the buildings will increase in the future due to expected climate changes and increased intensity of the urban islands. Thermo-active building systems show a high potential for reducing energy needs for cooling of the buildings. This article presents an experimental study of natural and mixed convection over thermally activated cooling wall. Mixed convection regime is generated by ventilation supply air jet flowing through longitudinal ceiling slot downward parallel to the cooled wall. Experimental results were used for developing of multiparametric models for local convective heat transfer coefficients for natural and mixed convection. Those models were afterwards used in TRNSYS simulation tool for modeling of the thermal response and energy consumption for cooling of typical office room with thermal activated cooled wall. Decrease in energy usage resulting from more intense convective heat transfer in case of mixed convection is presented.

Experimental investigation of model predictive control-based rules for a radiantly cooled office

A novel hybrid approach for supervisory control was applied to a test cell with thermo-active building systems and fan-assisted natural ventilation. Model predictive control was first used to identify combined thermo-active building systems and ventilation control strategies that maximized cooling energy savings while preserving thermal comfort. A rule extraction process using classification and regression trees then yielded supervisory rules capable of reproducing nearly all of the energy and comfort benefits of the model predictive control solutions when simulated. An experimental test of the rules was conducted on the same facility, yielding 40% average cooling energy savings compared to a base case, with comparable comfort. A variety of model input mismatches, including weather, model parameters, internal gains, and imperfect weather forecasts, degraded the performance of the rule significantly under experimental conditions, and analysis suggests that energy savings could have been nearly double had these factors been eliminated.

Predictive pre-cooling of thermo-active building systems with low-lift chillers

This article describes the development and experimental validation of a data-driven model predictive control algorithm that optimizes the operation of a low-lift chiller, a variable-capacity chiller run at low pressure ratios, serving a single zone with a thermo-active building system. The predictive control algorithm incorporates new elements lacking in previous chiller pre-cooling control optimization methods, including a model of temperature and load-dependent chiller performance extending to low-pressure and part-load ratios and a data-driven zone temperature response model that accounts for the transient thermal response of a concrete-core radiant floor thermo-active building system. Data-driven models of zone and concrete-core thermal response are identified from monitored zone temperature and thermal load data and combined with an empirical model of a low-lift chiller to implement model predictive control. The energy consumption of the cooling system, including the chiller compressor, condenser fan, and chilled-water pump energy, is minimized over a 24-h look-ahead moving horizon using the thermo-active building system for thermal storage and radiant distribution. A generalized pattern-search optimization over compressor speed is performed to identify optimal chiller control schedules at every hour, thereby accomplishing load shifting, efficient part-load operation, and cooling energy savings. Results from testing the system's sensible cooling efficiency in an experimental test chamber subject to the typical summer week of two climates, Atlanta, GA, and Phoenix, AZ, show sensible cooling energy savings of 25% and 19%, respectively, relative to a high efficiency, variable-speed split-system air conditioner.

Energy and efficiency analysis of environmental heat sources and sinks: In-use performance

A detailed analysis of the heating and cooling performance of environmental heat sources and sinks is presented for 12 low-energy buildings in Germany. In particular, the analysis focuses on the given temperature levels and the efficiency performance of the environmental heat sources and sinks in summer and winter. The investigated buildings employ environmental heat sources and sinks – such as the ground, groundwater, rainwater and the ambient air – in combination with thermo-active building systems (TABS). These concepts are promising approaches for slashing the primary energy use of buildings without violating occupant thermal comfort. A limited primary energy use of about 100 kW h prim/(m net 2 a) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, comprehensive long-term monitoring in fine time-resolution occurred over a period from two to five years. An accompanying commissioning of the building performance took place. Measurements include water supply and return temperatures of the environmental heat sources/sinks, the generated heating and cooling energy, efficiencies of the system, and local climatic site conditions. The comparative evaluation of the systems in all buildings identifies weak points and success factors of the plant. Besides, it characterizes the single component and points out further potential for optimization measures. The annual efficiency performance of the geothermal heat sources and sinks results in a seasonal performance factor of 8–10 kW h therm/kW h end, where the end energy use is electricity. The ground, groundwater, rainwater and even the ambient air constitute efficient heat sources/sinks. Energy is needed only for distributing the heat and cold and not for its generation. The choice of suitable plant components, the accurate design of the hydraulic system and the correct dimension of the environmental heat source/sink play a central role in achieving higher efficiencies.

Building signatures: A holistic approach to the evaluation of heating and cooling concepts

Abstract A sustainable and environmentally responsible building concept aims at a high workplace comfort, a significantly reduced heating and cooling demand, a high-efficient plant system, and the use of renewable energy sources to condition the built environment. This paper presents a comprehensive analysis of the heating and cooling concepts of 11 low-energy buildings in terms of energy use, efficiency and occupant thermal comfort. All buildings investigated employ environmental energy sources and sinks – such as the ground, ground water, rainwater and the ambient air – in combination with thermo-active building systems. A limited primary energy use of about 100 kWh prim /(m 2 net a) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, a comprehensive long-term monitoring in high time resolution was carried out for two to five years, with an accompanying commissioning of the building performance. Measurements include the useful heating and cooling energy use, auxiliary energy use for the hydraulic system, as well as end and primary energy use, occupant thermal comfort and local meteorological conditions. A new methodology is proposed for a holistic approach to the evaluation of heating and cooling concepts, which not only considers the occupants thermal comfort, but also the useful energy consumption and the efficiency of the generation, distribution and delivery of heating and cooling energy.