Green roofs and roof gardens: ANIT and Isopan solutions

The roofing of a building can have different shapes and characteristics depending on the designer's requirements and climatic peculiarities. Undoubtedly, green roofs are a rapidly spreading solution today.
They are part of the flat roof type and have undisputed advantages in terms of both performance and environment. 

At a time in history when environmental sustainability is of particular concern, such solutions are making inroads into the architectural world and are increasingly being adopted by designers.

ANIT (National Association for Thermal and Acoustic Insulation) has produced an information manual in collaboration with Manni Group dedicated to the study of the biotechnical characteristics of a green roofing.

One of the advantages of a green roof is its insulating capacity, which fits in well with the Association's main objectives: the dissemination, promotion and development of thermal and acoustic insulation in building construction as a tool through which to protect the environment and preserve people's well-being.

There are several aspects to focus on. For example, it is important to remember that a flat green roofing is a cost-effective solution on both an urban and a local scale.

At the urban level, it helps with:

• the reduction of the heat island phenomenon, i.e. the increase in temperature that occurs when moving from the outer areas to the city centre;
• the reduction of air pollution through the control of particulate;
• the improvement of urban furniture. 
  

At the level of the individual building, the benefits converge on:

• winter insulation;
• mitigation of summer temperatures;
• the attenuation of rainwater runoff;
• the aesthetic improvement of the building.

Minimum requirements and energy performance of green roofs

The Ministerial Decree of 26/06/2015 prescribes minimum requirements to be met in the construction of green roofs in order to control winter and summer energy performance and make a hygrothermal analysis of the package making up the stratigraphy.

These requirements concern:

• the control of the average and periodic thermal transmittance;
• the risk analysis of mould formation and interstitial condensation;
• the overheating risk analysis. 

There are three mechanisms, ANIT specifies, through which a green roofing increases energy performance compared to traditional roofing:

1. Control of solar absorption: the presence of vegetation improves radiative exchanges and mitigates temperature fluctuations, thereby limiting the risk of summer overheating;
2. Hygrometric accumulation/release: the greenery and the layers of which the roof is composed cause the environment to accumulate moisture that is released over time with the effect of dampening summer energy flows;
3. Thermal insulation: the materials that make up the stratigraphy of a roofing can protect the underlying environments from winter and summer temperature variations.

Improving performance with Isopan GreenROOF

A correct evaluation of the stratigraphy is essential to achieve high performance levels.
Thus, a sandwich panel roof exploits the characteristics of insulating panels to mitigate energy exchange.

This is what Isopan Greenroof proposes: a solution for cladding using an insulating material. Greenroof is a complex system made of materials that work with each other in harmony.

Adapting to flat roofs, Greenroof rests on a filtering geotextile element and on draining components in contact with the Isodeck PVSteel panel.

This solution uses sandwich panels with a polyurethane foam (PU) or rock mineral wool (MW) insulation core. The external sheet is coated with a protective, waterproof film, in PVC or TPO (thermoplastic olefin-based elastomers).

This green dry roofing system ensures:

• thermal insulation and soundproofing;
• waterproofing;
• resistance to weathering;
• ability to retain particulate;
• bioclimatic improvement;
• energy savings;
• roofing protection;
• added value for the building.
  

ANIT has identified the essential criteria and guidelines for the correct construction of green roofing and roof gardens.

Manni provided concrete answers in terms of applicable materials and construction systems.

A strategic combination to create buildings that spend less, are sustainable, more beautiful and more efficient.