Efficiency factors are here defined as the thermal energy performance indicators of the space heating. Until recently, the efficiency factors were assumed as one value for space heating located in any climate. This study addresses the problem of how the outdoor climate affects the efficiency factors of a space heating equipped with 1D model of hydronic floor heating. The findings show how the efficiency factors, computed with two numerical methods, are correlated with the solar radiation. This study highlights the paradoxes in understanding the results of efficiency factors analysis. This work suggests how to interpret and use the efficiency factors as a benchmark performance indicator.

In this study efficiency factors measures the thermal energy performance for space heating. This study deals with the influence of control strategies on the effriciency factors of space heating and its distribution system. An adaptive control is developed and applied to two types of heating curves (linear and non-linear) for a low-energy building equipped with renewable energy sources. The building is modelled with a hybrid approach (law driven + data driven model). The design of the floor heating is calibrated and validated by assessing the uncertainty bands for low temperatures and mass flow rate. advantages and disavantages of linear and non-linear heating curves are highlighted to illustrate their impact on space heating thermodynamic behaviour and on the efficiency factors of the space heating system.

Practical application: The study reveals that applying commercial building energy simulation software  is worthwhile to determine reliable performance predictions. Oversimplified building models, in particular when considering building thermal mass, are not capable of simulating the thermodynamic response of a building subjected to different control strategies. The application of different heating cuirves (linear and non-linear) to massless building models leaves the amount of mass flow rate delivered to the space heating unchanged when the building is subjected to sharp variations of the outdoor temperature. © The Chartered Institution of Building Services Engineers 2019

There is a major need of cost-effective renovation that leads to lower energy consumption and better environment. This article shows the results from a pilot case of a newly developed prefabricatedbuilding system. It is an industrially prefabricated insulated wooden element adapted to renovationand upgrading of building envelopes. The renovated building is a one-story office building located in Skellefted in the north of Sweden. Energy performance, thermal bridges, risk of moisture problems, LCA, applicability of the renovation method and assembly time were evaluated during the planning and execution of the renovation. Results from this case show that the elements were very light and easy for one person to handle at the building site. There is a great potential to reduce assembly time with improved joints and element sizes adapted to the building as well as improved batch packaging from the factory. With 100 mm insulation, the renovation gives a certain energy savings, and LCA calculations show that the reduction of climate impact due to reduced heating energy used during a service life 50 years corresponds to the climate impact of the renovation measures. The risk ofmicrobial growth can be regarded as small.

A common component of many building heating systems is a thermostat that controls the power on the radiators by changing the mass flow and/or temperature of the feed water. In some cases, these old thermostats malfunction or do not work quite as they should. This can contribute to large indoor-temperature fluctuations, which in turn can lead to unnecessary energy use and poor thermal indoor climate.

The goal of this paper is to develop a thermal dynamic model of hydronic radiators as well as a thermal dynamic building model to build Simulink models and investigate different control strategies to control the indoor temperature. By adapting better control strategies, one can reduce indoor-temperature fluctuations and reduce energy use.

The results of simulations in this paper suggest new ways of thinking concerning building a model of hydronic radiators and controlling them and that the temperature control of the studied building will be improved by using a well-functioning thermostatic radiator valve (TRV) instead of a poor-functioning TRV. The smaller fluctuation of the indoor temperature when using a well-functioning TRV compared to a poor-functioning TRV results in better indoor climate. Different types of TRV failures might give rise to large indoor-temperature oscillations, very high/very low indoor temperature and/or high energy use. In some cases, a poor-functioning TRV results in unreasonably high indoor temperatures and high energy use, and in other cases it might result in very low indoor temperatures, whereas the difference in performance when using well- functioning controllers (P and PI) is marginal. © 2015 juniper publishers,

In this paper a model of a high-rise building is constructed in the simulation program IDA ICE. The model is based on an IFC-model of a demonstration building constructed in Ljubljana, Slovenia, as part of an EU-project, EE-high-rise. The model's energy performance was simulated for four cities: Umeå (Scandinavia), Ljubljana (Central Europe), Sibenik (Mediterranean) and Dubai (The Persian Gulf). Furthermore, the climate envelope of the building was modified with the aim to improve the model's energy performance in each of the regions. The results were evaluated according to the energy requirements of passive house standard by the German Passive House Institute. The analysis suggests that the reference building model, which itself incorporates several energy efficient components, was unable to meet the German passive house standard in none of the four cities (Umeå, Ljubljana, Sibenik and Dubai) studied. By providing a combination of energy saving measures, such as modifications of thermal resistance of building envelope, the building may be able to meet the passive house standard in Ljubljana. The analysis concludes that the reduction in window area results in reduction of both heating and cooling demand. Increase in the thickness of the insulation and the thermal resistance of windows reduces the space heating demand for Umeå, Ljubljana and Sibenik (not applied for Dubai) while increasing the cooling demand for these cities. Increased airtightness has marginal effect on heating and cooling demand for all investigated cities. Reduced thermal resistance of windows will decrease cooling demand for Ljubljana, Sibenik and Dubai (not applied for Umeå). Reduced insulation thickness (not applied for Umeå) will decrease cooling demand for Ljubljana and Sibenik but not for Dubai. Reducing the insulation thickness may often result in reduced cooling demand for moderately warm countries since the average outdoor temperature could be lower than the indoor temperature during part of the cooling season. In those situations a reduced insulation thickness can cause heat flow from the relatively hot inside to the colder outside. However, for hot climates like in Dubai where outdoor temperature is higher than the indoor temperature for most of the year, reducing the insulation thickness will increase the cooling demand. This result suggests that the insulation thickness must be chosen and optimized based on heating and cooling demand, internal heat gain, and outdoor climate. © 2016, Tsinghua University Press and Springer-Verlag Berlin Heidelberg.

Open-space office/laboratory are quite common in Scandinavia and they are usually designed for multipurpose work. There are office area where is possible to work standing up and in the same time to work at the desk. For this purpose a hybrid heating system made by electric convectors and panel radiators is investigated. Two step response tests of the hybrid heating system are performed at the laboratory of Umeå University. The first test is executed during the week, disturbances from heat sources degrading the quality of the results. The second test is performed during week-end. The error analysis shows a maximum discrepancies of +0.6 °C between measured and simulated data. However, a thermal time constant of the room can be deducted and use it for controlling purposes.

This paper shows the tolerance of thermal parameters addressed to a building simulation model in relation to the local control of the HVAC system. This work is suitable for a modeler that has to set up a building simulation model. The modeler has to know which parameter needs to be considered carefully and vice-versa which does not need deep investigations. Local differential sensitivity analysis of thermal parameters generates the uncertainty bands for the indoor air. The latter operation is repeated with P, PI and PID local control of the heating system. In conclusion, the local control of a room has a deterministic impact on the tolerance of thermal parameters.

This paper shows a transient model of a hydronic panel radiator modelled as a system of multiple storage elements. The experiment´s results suggest the more suitable technique for modelling this technology. The panel radiator is modelled numerically with eight thermal capacitance connected in series by keeping a memory of the heat injected in the thermal unit. The comparison of the performance among lumped steadystate models and transient model, in terms of heat emission and temperature of exhaust flow, shows the potential of the latter approach. To conclude, (1) the transient phase is essential for modelling stocky panels, and (2) this type of modelling has to be addressed for evaluating the performance of low energy buildings.

This paper shows a detailed transient model of a panel radiator considered as a system of multiple storage elements. The experiment records the temperature surface of the panel in the process of heating up. The qualitative results of the experiment suggest the more appropriate technique for modelling this technology. The transient model performs the modelling with horizontal thermal capacitances connected in series. This model calculates the temperature of exhaust flow, heat emission towards indoor environment, temperature gradient on panel surface, dead and balancing time identified numerically on the chart.