G. Carrilho da Graca1,2*, A. Augusto1, M. Lerer2

University of Lisbon, DEGGE. 2NaturalWorks, Lisbon.
Corresponding Author: gcg@natural-works. com

Abstract

The Portuguese education ministry is in the process of modernizing the country’s high schools. The first phase of this operation comprises 172 buildings that will be rehabilitated and expanded. This initiative aims to improve indoor comfort in the schools (lighting, acoustics, ventilation and thermal comfort) as well as the environmental/energetic performance of the buildings [1]. This large rehabilitation effort coincides with the recent transposition (04/2006) of the 2002/91/CE directive on the energy performance of buildings. This study evaluates the possibility of integrating photovoltaic solar panels (PV) on the school roofs, creating a distributed renewable electrical energy production system. The expected PV generated electricity and the resultant reduction in CO2 equivalent emissions are estimated. Electrical production and avoided emissions will range between 20 and 31GWh/year, and 7 to 11 MtonCO2 /year, depending on the area of the system. The reduction in the net electrical energy consumption of the schools can exceed 60%.

Keywords: photovoltaic, integration, emissions

1. Introduction

Most of the electricity consumed in Portugal is produced in large power stations (thermal, hydro) usually located far from the demand, resulting in relevant power losses in the grid (around 10%). The existing energy infrastructure must be improved to meet increased demand with reduced emissions. In this scenario distributed renewable electrical energy production systems are attractive, reducing power losses in the grid and decreasing dependance on fossil fuel. As expected, most of the portuguese high schools are integrated in populated areas and have large roof to floor area ratios (0.2-0.3), making them suitable to PV integration in the roofs. Integration of renewable energy systems in schools is also important from an educational perspective as the systems become part of the daily life of the students.

This large school rehabilitation effort coincides with the recent transposition (04/2006) [2][3][4] of the 2002/91/CE [5] directive on the energy performance of buildings. This new legislation imposes limits on primary energy consumption as well as thermal comfort standards. As in most working environments, improved thermal conditions should also improve the performance of students and teachers. Still, as most schools currently have limited or no climate control systems and poor ventilation, the introduction of ventilation and air conditioning systems will result in increased energy costs. In this context the PV system may have the additional advantage of reducing the energy bills that schools will be faced with after the renewal process.

In order to evaluate the feasibility of this system we will answer the following questions:

• What is the area available for solar energy collection (roof area)

• What is the cost and payback of the PV systems

• What is the the impact in the electrical energy demand of the schools

• What is the reduction in overall Portuguese CO2 emissions.