Thermal Insulation and Energy Efficiency

According to DM 26/06/2015 (Annex 1 - minimum energy performance requirements), UNI/TS 11300 (parts 1–5) and European product standards (EN 13162–EN 13171 for insulation materials), walls must achieve a thermal transmittance (U-value) not exceeding the limits prescribed for the relevant climate zone. The Energy Performance Certificate (APE) must be prepared in accordance with D.Lgs. 192/2005 and subsequent amendments.

1. Check the type and thickness of insulation material against the design specifications and product data sheet.

2. Verify the CE marking of the insulation material and the Declaration of Performance (DoP) with the declared thermal conductivity value (lambda D).

3. Check the continuity of the insulation layer, paying particular attention to joints, corners and junctions with windows and floors.

4. Check for the absence of thermal bridges not accounted for in the energy calculation (UNI EN ISO 10211, UNI EN ISO 14683).

5. For external thermal insulation composite systems (ETICS), verify compliance with ETAG 004 / EAD 040083-00-0404 and correct application (bonding, mechanical fixing, reinforcing mesh, finishing).

6. Carry out a thermographic survey (UNI EN 13187) to identify installation defects and thermal bridges.

- Insulation thickness less than that specified in the energy design.

- Discontinuities in the insulation layer causing thermal bridges.

- Thermal bridges at balconies, columns and perimeter beams not corrected.

- Insulation material damaged by moisture due to missing or incorrectly positioned vapour barrier.

- ETICS system with insufficient or missing mechanical fixings.

According to DM 26/06/2015, UNI/TS 11300-1 and product standards (EN 13162–EN 13171), roofs and floor slabs above unheated spaces must meet the thermal transmittance limit values prescribed for the climate zone. UNI 11715 provides guidance for the design and installation of thermal insulation with insulation materials in cavities, externally and internally.

1. Check the type, thickness and correct installation of the insulation material on the roof or floor slab.

2. Verify the continuity of the insulation, especially at skylights, chimneys, vents and perimeter edges.

3. For flat roofs, check the correct position of the insulation layer relative to the vapour barrier and waterproof membrane (warm roof, inverted roof).

4. For pitched roofs, check the underside ventilation (if specified) and the presence of the breathable membrane or underlay.

5. Verify correct vapour barrier management (position, continuity, joint sealing) according to UNI EN ISO 13788.

6. Check for the absence of interstitial condensation through calculation according to UNI EN ISO 13788 (Glaser method) or dynamic simulation.

- Discontinuous roof insulation at penetrating elements (chimneys, antennas, vents).

- Vapour barrier absent, damaged or positioned on the cold side.

- Excessive compression of insulation material reducing its thermal performance.

- Insufficient underside ventilation in pitched roofs.

- Thermal bridges at roof perimeter edges (roof-to-wall junction).

According to DM 26/06/2015, UNI/TS 11300-1 and UNI EN ISO 9972 (pressurisation test - Blower Door Test), the airtightness of the building envelope contributes significantly to energy efficiency. For nZEB (Nearly Zero Energy Building) buildings, good airtightness is essential. Mechanical ventilation with heat recovery (VMC), if specified, must comply with UNI 10339 and UNI EN 16798-1.

1. Check the airtightness of joints between windows and masonry (sealing with tapes or membranes according to manufacturer instructions).

2. Verify the sealing of service penetrations through the envelope (pipes, cables, ducts).

3. Check the continuity of the airtightness layer at structural joints and junctions between different elements.

4. Carry out a Blower Door Test according to UNI EN ISO 9972, if required by the design or energy certification.

5. For mechanical ventilation systems (VMC), check correct installation, airflow balancing and compliance with UNI 10339.

6. Verify that heat recovery units (if specified) are installed and operating according to the mechanical design specifications.

- Air infiltration at joints between windows and masonry.

- Unsealed service penetrations through the heated envelope.

- Airtightness compromised at roof level (cable passages, structural penetrations).

- Unbalanced VMC system with airflow rates not conforming to the design.

- Air permeability values (n50) exceeding the limits set in the energy design.