○ Repeated (often found within the structural component of the enclosure and considered in the overall U-value calculation [e.g. steel and/or wood studs].)
○ Linear (expressed as a Psi value [Ψ] and calculated using a 2D thermal modelling software, found along the length of the enclosure occurring mainly at component joints, edges, and transitions within the building enclosure [e.g. a window-to-wall connection or slab edge].)
○Point thermal bridge (calculated using a 3D thermal modelling software and expressed as a Chi Value [X], these occur at isolated points within the enclosure [e.g. insulation attachments and/or fasteners].)
- High-performance windows—The use of triple-pane, high-performance windows that are Passive House certified are recommended for compliance, because this shortens the building certification process. Window-to-wall ratios are calculated and determined based on the orientation, glazing type, and shading mechanism to take maximum advantage of passive solar gains without risking overheating.
- Airtight enclosure—A leaky building enclosure leads to excess heat transfer, cold spots, and the potential for condensation. To achieve a continuous, airtight enclosure, close attention to detail is required at all joints and penetrations. The airtightness of a Passive House is measured by means of a blower door test.
- Heat recovery ventilation—Appropriate mechanical ventilation systems are critical to ensure clean and fresh air intake and occupant comfort. High performance energy recovery systems (energy recovery ventilator [ERV] or mechanical ventilation with heat recovery [MVHR]), required for Passive House, help reduce energy losses by taking advantage of heat energy from extract air.
- Building orientation—The orientation of a building is a crucial element in Passive House design to help with managing solar gains and losses. It is equally important to consider the influence of seasonal prevailing winds, as well as the effects of tree and building shading, on the overall performance of the building. These factors greatly impact the energy efficiency and comfort of the space and must be carefully considered during the design process.
Building enclosure requirements
- U-value recommendations:
○Opaque wall and roof U-value ≤ 0.15 W/m²K (0.03 Btu/F•hr•sf)
○Fenestration (triple-pane windows) Ug-value ≤ 0.80 W/m²K (0.14 Btu/F•hr•sf) and G-value:
0.5 to 0.62
- Thermal bridge free:
○Linear thermal bridge = Ψe ≤ 0.01 W/mK
○Point thermal bridge = X ≤ 0.005 W/m²K3
- Airtightness:
○≤ 0.6 ACH @ 50Pa
The benefits of Passive House and stone wool
Passive House buildings incorporating stone wool insulation contribute to performance objectives and allow for considerable design freedom in the building envelope design.
Depending on the construction type, above-grade wall assemblies can be designed using either only exterior ci or in combination with interior insulation to create a split-insulated assembly. For wall studs, stone wool stud cavity insulation (thermal batts) can be friction fit between studs.
Semi-rigid and rigid stone wool boards are a beneficial option as ci for above-grade rainscreen wall assemblies. Water repellent yet vapour permeable, they can be installed on the exterior side of a wall assembly.
In high-performance roof systems, high density stone wool roof insulation boards contribute to excellent thermal performance, superior acoustic performance, and fire resilience. Stone wool boards also have a much lower co-efficient of expansion and contraction, which results in increased dimensional stability over temperature changes and, therefore, minimal gapping between boards. This is an important characteristic contributing to the performance and durability of the roof assembly. By contrast, products with less dimensional stability (e.g. foam plastics) can experience greater expansion over time, larger gaps between boards and, therefore, decreased effective thermal resistance.
I hope you have great pest control, otherwise, mice and rats will nest in that wool.