While the Italian standard UNI 11235:2015 establishes minimum performance criteria, the thermal resistance of the growing medium of green roofs is not included in national regulations. Instead, thermal transmittance limits for roofs are obtained by referring to other stratigraphic layers. In the absence of specific national and international standards for laboratory calculations of the thermal performance of growing media for green roofs, a multi-year laboratory testing campaign was carried out on 8 samples which aimed to define the thermal resistance reference values of growing media as a function of density and water content. Thermal conductivity varies between 0.046-0.179 W/mK for dry samples as a function of density and between 0.046-0.47 W/mK as a function of moisture content. Defining a reference method, laboratory tests and restitution of the output in performance curves, was based on 108 tests carried out according to and deviating from the standard based on both guarded hot plate and heat flow meter methods. The significance of the results has prompted researchers and industrial partners to engage in further investment and ongoing tests in this area, targeting the definition of a standard laboratory method to be presented worldwide.

Green roofs are one of the most extensively investigated roofing technologies. Most of the bibliographical studies show results of researches focused on the analysis of different configurations of green roofs, but only few researches deal with the calculation of the growing media thermal resistance using laboratory tests. From 2009 to 2013, ITC-CNR, the Construction Technologies Institute of the National Research Council of Italy, carried out a first laboratory experimental campaign focused on the definition of thermal performances curves of growing media for green roofs as a function of both density and percentage of internal moisture. During this campaign, the experimental results underlined some existing gaps, such as the absence of specific standards concerning the sample laboratory preparation, the absence of shared references concerning the compaction level reached by samples in real working conditions and the evaluation of the internal moisture content of growing media exposed to atmospheric agents. For this reason, the ITC-CNR has set up a second experimental campaign focused on the solution of the gaps underlined by the first phase concerning the preparation of samples for the laboratory calculation of the thermal resistance of growing media for green roofs. This paper proposes and presents methodological approaches, methods and new test devices implemented to solve these gaps, and the results obtained.

The scientific community, along with the worldwide governments, debate about the performances of buildings for decades and today the subject is still of topical interest. The recent regulatory framework requires increasingly high energy-efficient buildings in order to reduce the overall impact of building sector and to improve the user’s well-being. Several stakeholders are called upon to contribute to this end. The collaboration between the professional, industrial and scientific sectors is an engine of this challenge. Following this path, the Construction Technologies Institute (ITC) of the National Research Council of Italy (CNR) has recently developed a zero energy laboratory with the aim of creating the best platform where companies of the building sector and research bodies can share their expertise for the development and the test of products and systems to reach the Zero Energy Building (ZEB) standard. The paper focuses on the design and testing phases of the laboratory. High performance envelope, efficient HVAC and renewable energy systems are the technical pillars of the laboratory. Several characterization tests have been carried out in order to choose the most suitable technical solutions. The integrated solutions (products and systems) are tested through a continuous monitoring: energy and the Indoor Environment Quality (IEQ) variables measurements are performed.