Geothermal heat pumps in the Maltese Parliament in Valletta
Overview
The Maltese Parliament in Valletta was built between 2011 and 2025 with environmental considerations playing a key role in the design and construction of this building from the start. Almost the Parliament’s entire cooling and heating needs throughout the year are covered by a geothermal heat pump system. The building is part of a project called “City Gate” which encompasses the area around the Parliament including a theatre and was designed by the architect Renzo Piano.
The geothermal system
The geothermal system consists of 40 boreholes sunk into rock to depths of 140 meters, which is 100 meters below sea level, geothermal heat pumps, and 600 square meters of solar panels located on the roof allowing the heat pump to run on renewable electricity. This allows the building to generate up to 100% of its own energy needs for heating during the winter and 80% for cooling in summer.
Thanks to its design, the building reaches high energy efficiency standards above the legal requirements. The stone façade heats up less and allows natural ventilation. In addition, irregularities on the façade create shadows, reducing the surface temperature. Thus, by combining passive design with the use of on-site renewable energy sources, the House of Parliament is a nearly zero-energy building.
Summary
Type of system: geothermal heat pumps combined with solar panels
Borehole depth: 140 meters (100 meters below sea level)
Number of boreholes: 40
Energy demand covered by the geothermal heat pump system: 100% of heating and 80% of cooling