NY S09921

Amends Executive Law Section 378 to permit unvented attics and unvented enclosed rafter assemblies insulated with air-impermeable insulation (R-30, maximum U-Factor of 0.038) to meet state energy conservation code requirements.

Requires homes using this insulation method to achieve a blower door test result of less than 2.5 ACH50 and install a positive, balanced, or hybrid whole house mechanical ventilation system.

Mandates exposed roof rafters be insulated with minimum R-3 unless directly covered by drywall or finished ceiling, or unless continuous insulation is installed above the roof deck.

Requires all indoor heating, cooling, ventilation equipment, and ductwork to be located inside the building thermal envelope.

Takes effect 180 days after enactment; directs the State Fire Prevention and Building Code Council to promulgate necessary standards immediately.