Ventilated Active Thermoelectric Envelop

Basic information

Project Title

Full project title

Integration development of a Ventilated Active Thermoelectric Envelope (VATE)

Project Description

Project Region

Pamplona, Spain

EU Programme or fund

Description of the project

Summary

The use of thermoelectricity in buildings represents a disruptive alternative for indoor thermal needs as it is a technology that allows the elimination of refrigerants. In this line of research, authors of this study have worked on the design and construction of several Ventilated Active Thermoelectric Envelope (VATE) prototypes. A VATE is an industrial-scale modular prototype designed to be installed in the build- ing façade and thought to be an alternative solution for heating and cooling in Net Zero Energy Buildings.

Previous prototype modules have been tested to assess their heat power and performance in heating and cooling mode, which could be considered an initial approach towards the solution of designing VATEs that can be replicated. These works have resulted in an improvement of the COP of the system, the relationship of the Peltier cells and the ventilated façade, as well as with the interaction with photo- voltaic systems. However, the problem of the thermal bridge when the VATE was turned off remained.

Taking into consideration the lessons learned from previous construction solutions, the system has been redesigned, prioritizing in this case the reduction (not elimination) of the VATE thermal bridge. This article describes and justifies the solutions developed, presents the results achieved for heating and cooling, and raises points about what could evolve from this issue.

Key objectives for sustainability

Authors of this study have been working on the design of a Thermoelectric Cooling and Heating Unit (TCHU) since 2009, which was later defined as Ventilated Active Thermoelectric Envelope (VATE). All of these previous projects were aimed at finding an innovative, modular and autonomous heating and cooling system for buildings embedded in the building envelope. The methodology used throughout the different studies was based on the construction of real scale prototypes monitored under real conditions.

Thermoelectricity is based on the use of Peltier cells, which currently have relatively small dimensions and low heat transfer capabilities. This means that in order to heat or cool a space it is necessary to use a considerable number of them. As has been demonstrated beforehand, this poses a problem for certain uses, but it also offers the advantage of modulation, so if the operation of a part is known, the results can be extrapolated to the entire system.

Key objectives for aesthetics and quality

In this article, the latest optimized VATE design is presented, the drawbacks arising from the Peltier cell thermal bridge are faced and a new constructive design is proposed, with the following objectives:

- Describe in detail the optimization of the integration of a ther- moelectric module in the façade, improving the constructive system definition, the airtightness and thermal behavior.
- Optimize the thermoelectric system, components space, the electric board, the connections and control system.
- Analyze the operating behavior data for cooling and heating.

Key objectives for inclusion

Third real-scale VATE prototype (2016–2018). The objective of this prototype was to create a design which was modular (easy to assemble, P&P solution) and autonomous (PV panels) VATE. It represented an important step forward, especially in those aspects related to the thermoelectric control system. However, the design failed in several areas related to energy performance as a façade: there was a lack of airtightness as well as heat loss due to the lack of insulation and the thermal bridges generated by the Peltier cells. These two factors, together with an optimization of the number of cables and final laying, are perhaps the main advances of the prototype developed for this study compared to that previously mentioned.

Results in relation to category

This study represents another step forward for the integration of thermoelectric systems in building envelopes. Research suggests that a significant qualitative leap has been constructively achieved, but further development is needed to improve the selection and integration of fans, as well as their integration in other buildings during real use. It is also necessary to consider regulatory and economic aspects, because commercial development will not be a possibility if VATEs do not comply with these. It is worth mention- ing that the Technical Building Codes do not include these active facade solutions, which could discourage the development of innovative technologies, especially for companies in the building industry.

How Citizens benefit

A system without greenhouse gas emissions has been developed. We repeat: without greenhouse gas emissions!!! This system works better with photovoltaic systems than with conventional electrical supplies. So the project is 100% aligned with the actual interests of the European civil society.