DESIGN OF CONSUMMER THERMAL SUBSTATIONS FOR THE INTEGRATION OF DISTRIBUTED SOLAR TECHNOLOGIES IN DISTRICT HEATING SYSTEMS

In most cases, building service designers choose between Solar thermal (ST) and District Heating (DH) technologies for their integration in buildings. By doing so, only a fraction of the buildings within a particular district is used for ST, while at the same time energy intensity in DH networks can be reduced. In some cases, building-integrated solar thermal systems are connected to DH networks by means of dedicated pipes. In all these cases, sub-optimal situations are reached with lower fraction of renewable heat, reduced network strength and/or additional heat losses. In this paper, a consummer substation concept is proposed with reversible heat flow and net metering, which avoids local thermal storage in the solar loop. Adaptations required for multi-dwelling buildings are presented.European Commission's H2020, 768567, RELaTE

RELATED, A FLEXIBLE APPROACH TO THE DEPLOYMENT AND CONVERSION OF DH NETWORKS TO LOW TEMPERATURE, WITH INCREASED USE OF LOCAL SOLAR SYSTEMS

District heating (DH) systems are key systems for the de-carbonization of heating energy in European Cities. In order to allow for this transition, while guaranteeing competitive energy costs, conversion of DHs is required. DH operation temperature needs to be reduced in order to increase the performance of renewable systems and operation criteria needs to be adopted for the introduction of weather-dependent, distributed heat sources such as solar systems. This paper presents the RELaTED decentralized Ultra-Low Temperature DH network scheme, and its adaptation to several operational schemes such as new and existing DH networks, with different levels of complexity. Transitory phases in the conversion process are discussed.European Commission's H2020, 768567, RELaTE

Hybrid numerical and experimental performance assessment of structural thermal bridge retrofits

A methodological approach to the multi-dimensional heat transfer assessment of building envelopes is performed. The proposed method is particularly focused on thermally weak points in envelope-structure junctions and the assessment of envelope retrofit alternatives. Thermal performance in these spots is seldom assessed in energy audit processes, although it is one of the main heat loss paths in many insulated façade solutions. An envelope-slab junction case is presented, where multi-dimensional heat transfer occurs. The present paper proposes a methodology which allows for a hybrid experimental and numerical performance assessment in such circumstances. A numerical model is calibrated against experimental data, which is then modified to reflect various envelope retrofit solutions. Several possible analysis procedures are proposed, based on the capacities of transient thermal models.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 63718

Assessment of thermal performance and surface moisture risk for a rear-ventilated cladding system for façade renovation

Ventilated façade systems, incorporating thermal insulation behind a rear-ventilated cladding, constitute a popular renovation solution in warm European climates. For compliance with building regulations, their energy efficiency is usually obtained through simple onedimensional desktop calculations, which do not consider the impact of the support elements of the cladding penetrating the thermal insulation. This study assesses a ventilated façade system anchored over a solid concrete wall with adjustable stainless steel brackets. One-dimensional calculations are compared against three-dimensional numerical thermal modelling, evaluating the effect of insulation thickness (40–100 mm) and potential gaps in the insulation around anchors. Results indicate low risk of condensation and mould growth over internal surfaces. The additional heat flow induced by stainless steel anchors, which is not considered by simplified calculations, appears lower than for aluminium-based systems but can become significant as insulation levels increase. Ensuring the continuity of insulation around anchors is critical for keeping this additional heat flow at reasonable levels (8–13%). If gaps in the insulation are present around anchors, the additional heat flow increases substantially (25–70%) and pushes effective U-values above 0.4 W/m²K, thus resulting in unforeseen energy consumption and noncompliance with regulatory requirements in many European locations.This study has been partly developed within the InnoWEE research project. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 723916. The present paper reflects only the authors’ views and neither the Agency nor the Commission are responsible for any use that may be made of the information contained therein

Regression analysis of the energy consumption of tertiary buildings

Energy signature methods are applied over three tertiary buildings in the UK, Sweden and Spain, based on both simulations and experimental data, for pre- and post-retrofit scenarios. Variations in their energy profiles relate to differences in climate severity, usage pattern (continuous/discontinuous) and HVAC scheduling. This study discusses the impact of such particularities for obtaining a steady-state linear regression model of the dependence of heating energy load against climate data. The choices of dataset and time step have important implications for the results obtained.The research leading to these results has been partly developed within the RESSEEPE project, funded by the European Union's Seventh Framework Programme (FP7) under grant agreement no. 609377

Energy & economic assessment of façade-integrated solar thermal systems combined with ultra-low temperature district-heating

This paper conducts an energy and economic assessment of District Heating (DH) integrated Solar Thermal (ST) systems. An implementation with building-integrated ST collectors coupled to a Low Temperature District Heating (LTDH) system is studied, with special focus on unglazed collectors. ST heat is exploited in the building through direct use, while excess heat is delivered to the network. A novel control strategy for heat flows in the system is proposed. A meta-analysis of several DH configurations, interconnection schemes and installed ST capacity is performed in three different climates: Sevilla (Spain), Bordeaux (France) & Copenhagen (Denmark). Heat loads corresponding to buildings with various insulation levels and domestic hot water loads are assessed in hourly simulations. The proposed interconnection concept provides a variety of connection modes to the DH network, allowing up to a 50% increase in the provision of solar heat compared to an isolated ST system. Positive Return of Investment (ROI) for such a setup is achieved in 22% of the studied cases. The DH network is found to be a suitable heat sink in up to 25% of the buildings with ST systems installed.This project has received funding from the European Union’sHorizon 2020 research and innovation programme under grantagreement No 76856

Simulation of Unglazed Solar Thermal Systems Integrated into Façade & Combined with Ultra-Low Temperature District Heating

This paper presents a theoretical simulation of thermal and economical assessment of façade integrated Solar Thermal (ST) in combination with Ultra Low Temperature (ULT) District-Heating (DH). This paper is in line with existing R&D activities for the integration of unglazed systems in building envelopes, where facades provide an almost unexplored area for increasing solaractivated building envelopes. The combination of building-integrated solar systems with DH networks avoids the use of local storage and allows a novel combination of heat directionality, both from building to the heat grid and vice versa. A control algorithm for heat supply is presented, so that the performance of the overall system is the optimal. Energetic results from solar simulations and economic assessment derived from the balance of building energy demand and solar production are presented. Over a fullyear period the proposed unglazed system produces as much as 50% additional heat when compared with an isolated ST system and profitable economic metrics are reached over a simulation time of 20 years. Finally, it is concluded the heat sink nature of a DH network, for as many as 25-35% of the buildings connected to the DH includes ST system.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 768567

Experimentation under real performing conditions of a highly integrable unglazed solar collector into a building façade

In the current context of moving towards more sustainable construction, advanced façade systems that integrate solar collecting devices represent a commitment with future trends that combine renewable technologies with building skins. This paper describes a real experience when combining a novel unglazed solar collector based on sandwich panel technology, a heat pump and a controller that manages the different operation modes. Installed in the Kubik by Tecnalia testing building in northern Spain, the system has been monitored for several months in 2016, under an energy efficiency scope. The study will present measured values regarding the yield of the collector, performance of the heat pump and general efficiencies.The research leading to the results reported in this work has received funding from the European Union, RFCS Program, Research Fund for Coal and Steel project Building Active Steel Skin (BASSE, Grant Agreement no RFSRCT-2013-00026

Experimental Thermal Performance Assessment of a Prefabricated External Insulation System for Building Retrofitting

External Thermal Insulation Composite Systems (ETICS) are increasingly used for the energy-efficient retrofit of buildings. This paper evaluates the in-situ thermal performance of a prefabricated composite panel made of PIR and concrete, by full scale testing of a prototype installed at the KUBIK test facility. Experimental results from measurement show a reduction in the thermal resistance of the ETICS assembly compared to theoretical design values. A number of phenomena have been identified causing multidimensional heat flow of conductive and convective nature,such as thermal bridges at floor slabs and anchors, and thermal bypass of the insulation causing airflow behind the ETICS.The ETIXc project consortium, composed of Sociedad Financiera y Minera, S.A. FYM- HeidelbergCement Group and Prehorquisa. This research work has been aided by the EEA Grants special funding from the Financial Mechanism of the European Economic Area (2009-2014)

Unglazed Solar Thermal Systems for Building Integration, coupled with District Heating Systems. Conceptual Definition, Cost and Performance Assessment

In this paper, the energy performance of a Solar Thermal (ST) façade system is studied for its connection to a District Heating System. This concept allows for the direct use of ST heat in the building, while taking profit from the network for delivery/selling of excess heat and purchase of heat during periods of underproduction. The use of Unglazed Collectors for low-intrusive architectural interaction in façades is discussed. Studies are carried out on the heat production of the system and its capacity to cope with local demands. Economic studies are carried out in order to balance the investment and operational costs/profits of the system.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 768567