Our brand spanking new Student Showcase blog will feature guest bloggers from around the world who have used the <Virtual Environment> software to complete their studies. If you would like your work to be considered for the Student Showcase blog drop me an email at john.goucher@iesve.com.
Our first guest blogger is Fabio Favoino, a student of Building Engineering who is currently working as a researcher on innovative building envelopes at the Department of Energetic of the Polytechnic University of Turin. Fabio is set to present his paper at RoomVent 2011, a conference about ventilation in buildings, hosted in Trondheim, Norway, in June.
:: Zero Energy Building: evaluation of innovative ACTRESS façade through dynamic energy simulation ::
Several researches [IEA–ECBCS Annex 44 (2007) and (2010)] have demonstrated that, in order to overcome the limitation given by the existing technologies, the building as a whole system should be revisited as a more integrated organism, characterized by a “responsive” and “dynamic” behaviour. In particular Responsive Building Elements (RBE) represent a promising technology for achieving the requirements posed by the ZEB concept. Among other RBEs, Advanced Integrated Façades (AIFs) have been – and still are – widely investigated, especially because of the key role that the building envelope plays in controlling the energy and mass transfer between outdoor and indoor.
This MSc thesis work in Building Engineering consists in the energetic performance evaluation of an innovative AIF module, ACTRESS (ACTive, RESponsive and Solar), which has been conceived within a wider research activity on Responsive Building Elements, carried out by the TEBE Technology Energy Building Environment research group of the Polytechnic University of Turin, of which the author is part. The ACTRESS module is designed as a one story height prefabricated Multifunctional Façade Module, consisting of two sub modules (50%-50%), one opaque and one transparent. The opaque sub-module is constituted by an Opaque Ventilated Façade (OVF) equipped with axial fans for the hybrid (fan-assisted) ventilation of the cavity. The OVF integrates aSi PV panels on the outer surface, with a sandwich, made up of VIP and PCM layers, PV activated during winter. The transparent sub-system is made of high performance glazing: triple glazeing lowE (internal) with cavity lowE operable venetian blinds (outer cavity), and Argon gas (inner cavity).
The evaluation of the energetic performance was carried out with IES VE in order to assess the capability of a commercial software to simulate complex and dynamic building envelope components, one of the key limitation in their spread into the markets, together with costs.
:: IES simulation of the innovative ACTRESS façade module and results ::
ModelIT, SunCast, ApacheSim, MacroFlow and ApacheHVAC were used to model the different components of the AIF façade. The simulations showed important results. In the cooling season the façade is able to reduce the entering heat flux by more than 60% for the 50% of the occupation period, with an average improvement of 10% from NV to MV. The cumulated frequency analysis for the heating season shows that the façade has a high capability to preheat the cavity air, which can be used as Supply Air for the HVAC system, provideing the 20% of the heating plant load during winter. In the mid season the high values of preheating efficiency enable the use of cavity air as indoor environment supply air when (preheating efficiency) is between 1 and 2.
ACTRESS module improves the PV efficiency up to 10%, with a medium value of 5%, if compared to the electric efficiency of a BIPV on a vertical façade with no integration with any thermal system.
Comparing the ACTRESS module with a traditional façade the overall reduction of primary energy demand in an office building results in 52% less total energy demand (heating, air conditioning and electric), passing from 19,09 kWh/m3y to 9.09 kWh/m3y, with a significant reduction in heating loads EEh, due to the use of PV energy to activate the PCM in the OVF (almost 53%). While it is also remarkable how the electric consumption can be almost totally covered, 95%, on an annual basis by the PV electric production, already accounting for PCM and fan consumption. Furthermore it was evaluated the possibility to exploit the OVF preheated air as supply air for the HVAC system during heating and mid season. Thus increasing the heating energy saving by 8% in respect to ACTRESS façade with Outdoor Air Curtain ventilation. In this way more than 55% reduction can be achieved, with 8,55 kWh/m3y total energy consumption.
Concluding the ACTRESS module shows a very good performance, concerning both the sub-components behaviour and the overall building energy demand. This investigation highlighted a poor performance of IES VE in simulating innovative components, as proper modeling needed tips and shortcuts not known to junior and medium designer, and assumption which can jeopardize the energy simulation reliability and accuracy. Data on its actual performance will be collected through a yearly experimental campaign, which is just started, which will allow a validation of the assumptions done.