Nearly-Zero Energy Buildings are buildings with a very high energy performance. According to the Energy Performance of Buildings Directive (EPBD, Directive 2010/31/EU) the nearly zero or very low amount of energy required should be covered to a very significant extent from renewable sources, including energy from renewable sources produced on-site or nearby. While the Directive includes this general definition of the NZEB, it is up to the EU Member States to set up a detailed national application of this definition. The Directive requests also that by 31 December 2020 all new buildings are nearly-zero energy buildings and after 31 December 2018 all new buildings occupied and owned by public authorities are nearly-zero energy buildings.

In this way, RANK has previous experience via the European project BRICKER “Total Renovation Strategies for Energy Reduction in Public Building Stock” of the 7th Framework Program. BRICKER objective was to develop a solution to renovate existing public buildings. For that purpose, a series of active and passive solutions were developed and tested, including parabolic solar collectors (CSP: “Concentrated Solar Power”), ventilated facades, insulation systems with PCM (Phase Change Materials), biomass boilers, ORC machines and absorption/adsorption technologies.

The final solution consisted in a cogeneration system with a Rank® HTC2 machine powered by a biomass boiler. This cogeneration equipment is responsible for supplying most of the heat and electricity required by the building. The heat transfer fluid between the biomass boiler and the ORC module is thermal oil designed to be used at high temperatures. On the other hand, useful heat is produced as water at 70 °C, which is used in the HVAC system.

Rank® HTC2 machines are specially designed for cogeneration applications with high-temperature thermal needs, being able to generate electrical power of up to 90 kWe. As a result, the primary energy saving in this case is approximately 61%, and the associated carbon dioxide emission reduction is around 50%.