Façades play an important role in architecture, with deep implications in both the quality of the indoor environment and the appearance of the building. R&D in the field of energy conservation is moving toward advanced integrated façades (AIFs): these are innovative and dynamic façades deeply connected with the building equipment. Their dynamic features allow the energy performance of the façade to be optimized, adapting its behavior to different boundary conditions. The substantial lack of synthetic performance parameters to assess and to characterize the energy performance of AIFs is one of the main limitations to the widespread of these technologies. This inconvenience is due to the fact that conventional synthetic metrics (such as U-value and g-value) cannot be fully applied with these technologies. The research activity presented in the paper is an attempt to investigate new synthetic metrics able to characterize the thermal behavior of an AIF. A multiple linear regression (MLR) approach is adopted to identify synthetic parameters able to replicate the energy performance of the façade as a function of the main boundary conditions, e.g., solar irradiance and thermal gradients.

Abstract

This paper deals with the experimental assessment of the energy performance of two Advanced Integrated Façade modules (AIF) characterized by two very similar configurations. The two AIF modules were installed on the south-exposed façade of an outdoor test cell facility (a real-scale mockup of an office building) and continuous measurements were carried out for more than one year. Data collected during the experimental campaign were analyzed to evaluate the energy performance and thermo-physical behaviour of the AIF modules. The performances of the two systems were assessed by comparison and by means of conventional and advanced synthetic metrics.

The results of the activity point out the different performances of the two configurations, which only differs on the inner-side glazing (a stratified single clear glass pane vs a stratified low-e double glazed unit). It was demonstrated that just a single additional glass layer can contribute to substantially improve the energy performance of a quite complex façade technology. On average, the façade configuration with the stratified low-e double glazed unit shows the abatement of heat loss and of solar gain of about 30% during the whole year. Moreover, the reliability of some conventional and less conventional metrics in assessing the performance of dynamic façade technologies was also investigated. The results confirm that conventional metrics are not fully reliable when they are used to assess advanced building envelope components with high level of dynamic.

Responsive Building Elements (RBEs) are technologies for the exploiting at the building scale renewable energy sources and the opportunities offered by the environment. Among the RBE concepts identified by the IEA-ECBCS Annex 44, Advanced Integrated Façades (AIFs) is probably one of the most promising technologies. Important players in the field of the façade have started to develop integrated modular façade systems (Multifunctional Façade Modules - MFMs), with a dynamic behaviour and interacting with the other building services, in order to reduce the building energy consumption and maximize the indoor comfort conditions. In the frame of a research activity aimed at the development of solar and active building skin, a MFM has been conceived and a prototype realized for experimental evaluation. The work presented in this paper illustrates the first results of the experimental campaign on the RBE-MFM called ACTRESS (ACTive, RESponsive and Solar). The ACTRESS façade module is being tested by means of a Test Cell apparatus. The main physical quantities (e.g. heat fluxes, temperatures, transmitted irradiances, PV power, air flows, etc.) are continuously measured by means of more than 70 sensors placed on the mock-up. A detailed picture of the monitoring system is given with the description of the measurement procedures. Preliminary results concerning the behaviour of the system during summer and mid season are illustrated and discussed.

In order to be successful on the market, energy-saving measures for existing buildings need to be promoted with arguments that are directly relevant to the users. Initial marketing for energy retrofitting has been based on monetary profits from future energy savings. However, for most households in Europe, energy bills for the home account for only 3-4 percent of disposable income, hence are not a major concern. As a result of inappropriate promotion of energy savings for existing buildings, less than 1 percent of over 300.000 projects certified by BREEAM are refurbishments. Apparently, the promotion of energy retrofitting needs to be based on different grounds. It has been shown that people are particularly attracted to the idea of increasing the comfort and appearance of their homes, rather than carbon savings or long-term monetary profits. Therefore, the goal in this paper was to analyze the potential of linking energy-efficiency to an increase in housing quality.Once this relation is precisely defined, people will have a clear idea about the benefits of energy retrofits of their homes, thus be more motivated to make the investments.

The aim of the study was to define an energy supply solutions for a low-energy commercial building in cold climates. A new low-energy office building built with high quality building insulation better than the Norwegian passive building standard was analyzed by using EnergyPlus. The results showed that the heat pump solutions could be used to cover the building base load, while the peak load should be covered by additional energy sources. Due to a high indoor temperature caused by the high quality building insulation standard, an increase in ventilation air flow was necessary during the summer. To fully utilize the heat pump technology possibilities and avoid unnecessary use of the electric boiler, the control strategy without night setback was preferable. The techno-economic analysis showed that the best energy supply solution seemed to be an air-to-water heat pump without solar assistance, while a 50% increase in the energy price could make the solution with the solar collector economically attractive. A similar trend might be noticed for other building types under the same economic conditions, because the relative ratio between the savings and the total energy use would be similar.

Abstract

New buildings have to satisfy ever-tightening standards regarding energy efficiency and consumption. This results in higher insulation levels and lower air leakages that reduce heating demands. However, even at moderate outdoor temperatures these buildings are easily warmed up to such a degree that in order to ensure acceptable indoor environment quality, removal of excess heat becomes unavoidable. Use of electric energy related to mechanical cooling is considered incompatible with achieving zero energy buildings (ZEB). The use of ventilative cooling (VC) in combination with mechanical cooling means energy consumption reduction due to lower use of mechanical ventilation and cooling system.
This paper examines the application of ventilative cooling solutions in cold climates through simulations of an existing detached single family house in Norway, the ZEB Living Lab at NTNU/SINTEF. The house has computer controlled motorized windows. This will enable natural ventilation in some part of the year and could then reduce the energy use of fan power. The openable window are placed at the north and south facades and this enables considerably cross ventilation and also stack ventilation as some windows are placed four meters high.
IDA ICE program will be used to calculate the energy consumption of the baseline simulation: demand controlled ventilation with variable air volume and mechanical cooling. By means of using CONTAMW the airflow profiles while using controlled window opening are calculated and used as input profiles in IDA ICE to calculate the energy consumption while using hybrid mode ventilation.
Results show significant energy savings when using ventilative cooling. Due to the low outdoor temperatures in Norway the use of ventilative cooling remove mechanical cooling demands almost completely. The reference for comparison has been the European standard EN15251 (class II).
Ventilative cooling is proven to be relevant in combination with mechanical ventilation and will be crucial to achieving energy targets for new zero energy buildings while the indoor climate is maintained.