Abstract

The demands for both thermal comfort and reduced energy consumption in buildings have become a major driving force for the increased use of advanced building automation and control systems (BACS). In the on-going development of Zero Emission Buildings (ZEBs), it seems to be a common understanding that such systems are needed in order to save energy and reach the zero emission goals, and that energy consumption for their operation is negligible compared to the building needs and the energy saving potential BACS causes. However, sensors and actuators in automation and control systems require electricity to operate, and both the environmental impact related to this operation, and the manufacturing and maintenance of electronic components (including wiring) is not well understood in a Life Cycle Assessment (LCA) perspective, even though different standards give framework and methods for energy calculations and LCA of buildings. These standards unfortunately do not include or suggest default values for the auxiliary energy from different levels of BACS. Usually, in building simulation, these values are only assumed to be a part of a fixed internal gain, e.g. as in the Norwegian passive house standard, with no further considerations on the actual operating energy or the environmental impact it represents.

In this paper, auxiliary energy to operate a KNX-bus system for a planned passive house office building with demand control on room/zone level, is measured in a laboratory test. For typical room zones, as for a single office and a meeting room, the electrical standby power counts for respectively 0.91 and 2.00 kWh/m2∙y solely for operating the automatic system on room level. E.g., based on the electricity mix UCPTE, components needed to achieve automatic zone control equals 2.86 and 6.28 kWh/m2∙y of non-renewable primary energy (PEFnon-ren). For the whole building; 0.85 kWh/m2∙y and PEFnon-ren = 2.67 kWh/m2∙y. Other PEF production factors will give different results which can have decisive implications on the development of the ZEB concept and the use of BACS in future buildings. The auxiliary energy for BACS should therefore be included when conducting energy simulations and evaluations of the environmental performance of Zero Emission Buildings.

The demands for both thermal comfort and reduced energy consumption in buildings have become a major driving force for the increased use of advanced building automation and control systems (BACS). In the on-going development of Zero Emission Buildings (ZEBs), it seems to be a common understanding that such systems are needed in order to save energy and reach the zero emission goals, and that energy consumption for their operation is negligible compared to the building needs and the energy saving potential BACS causes.

However, sensors and actuators in automation and control systems require electricity to operate, and both the environmental impact related to this operation, and the manufacturing and maintenance of electronic components (including wiring) is not well understood in a Life Cycle Assessment (LCA) perspective, even though different standards give framework and methods for energy calculations and LCA of buildings. These standards unfortunately do not include or suggest default values for the auxiliary energy from different levels of BACS. Usually, in building simulation, these values are only assumed to be a part of a fixed internal gain, e.g. as in the Norwegian passive house standard, with no further considerations on the actual operating energy or the environmental impact it represents.

Design principles in Net-ZEB considers the local energy infrastructure as virtual storage leading to large amount of energy exchange with the grid. Nonetheless, with high Net-ZEB penetration scenarios, such exchange could compromise the effectiveness of Net- ZEB concept in a total energy infrastructure. As the current market trends, heat pumps along with photovoltaics are seen as an emerging energy supply solutions in Net-ZEB buildings, effectiveness of an all-electric Net-ZEB (that is using air-to-water heat pump with photovoltaic) is analysed. Two concrete control cases of energy storage (compared to reference case) to assess Net-ZEB ability to self-consume vs. grid empowerment are studied. Results shows that introduc tion of storage buffer in such concept leads to a flexibility of almost 6 % in self-consumption and 13 % in grid-impact factor and in-turn provide significant manoeuvring space to the demand-supply balance at the grid level.

The Research Centre on Zero Emission Buildings - Annual Report 2012

Wood stoves are attractive for the space-heating (SH) of passive houses. Nevertheless, there are still questions about their integration. Firstly, the power oversizing of the current stoves and their long operating time may lead to unacceptable overheating. Secondly, it is also unclear how one stove can ensure the thermal comfort in the entire building. The paper investigates these aspects using detailed dynamic simulations (TRNSYS) applied to a detached house in Belgium. An 8 kW stove is assumed to be representative of the lowest available powers in the market. Results confirm that a large power modulation is important to prevent overheating. Opening the internal doors, a high building thermal mass and a heat emission dominated by radiation also reduce the overheating risk, but to a smaller extent. Besides, a single stove cannot enforce the thermal comfort during design weather conditions: a peak-load system is then needed. Using more standard conditions, a Typical Meteorological Year (TMY), the stove can mainly perform the SH but it then requires the internal doors inside the building to be opened. The temperature distribution between rooms is in fact dominated by the architectonic properties. Finally, the emission and distribution efficiency of the stove is also investigated.