The Nighttime Recovery Standard

1. The Core Mandate

All residential units must be capable of reaching a Safe Recovery Temperature of 26°C for at least 8 continuous hours between 10:00 PM and 6:00 AM.

2. The Science (Why?)

Tropical nights prevent cardiovascular reset.

“Mortality risk increases by ~10-60% during tropical nights.” — WHO Heat Guidelines

3. Implementation

3.1 Passive First

Before mechanical cooling is installed, landlords must install external shading on South/West facing windows.

3.2 The “Cool Room” Variance

If central AC is not feasible, the landlord may designate one “Recovery Room” that meets the standard.

Real-World Context:

• Paris, France: The city’s Heat Wave Action Plan identifies vulnerable populations and designates “îlots de fraîcheur” (cool islands) including air-conditioned public buildings where residents can seek refuge during extreme heat events.
• Phoenix, Arizona: The city operates Heat Relief Network with cooling centers and hydration stations, recognizing that nighttime heat stress is a public health emergency requiring infrastructure response.

4. Compliance Timeline

1. 12-Month Retrofit Clock: Within 12 months of ordinance adoption, every landlord shall file a compliance plan identifying which units already meet the 26°C recovery target and which require upgrades.
2. Seasonal Readiness Date: By 1 April of each year, property owners shall certify that passive shading, ventilation strategies, and any mechanical systems are operational before the first forecasted heat wave.
3. Emergency Activation: During officially declared heat emergencies, landlords must switch to the “Cool Room” schedule within 24 hours and notify tenants of the designated space.

5. Enforcement & Verification

1. Rental License Conditioning: No rental license, occupancy permit, or condominium registration shall be issued or renewed unless the owner submits the annual Nighttime Recovery Certification (temperature log plus shading inventory).
2. In-Unit Sensors: Housing inspectors shall deploy calibrated data loggers during random audits and whenever a tenant files a heat complaint. A single failed test triggers a correction order with a 14-day retrofit deadline.
3. Penalties & Tenant Protections: Owners that miss the correction deadline shall pay fines of €500 per dwelling per day and must provide temporary cooling or hotel accommodation at their expense. Third offenses escalate to license suspension and public disclosure on the municipal registry.

6. Metrics & Transparency

• Compliance Rate: Publish the percentage of certified units and highlight wards falling below 90% compliance.
• Health Outcomes: Track emergency room visits for nighttime heat stress and correlate with compliance data.
• Upgrade Pipeline: Report how many units received passive shading versus mechanical cooling so future subsidies can be targeted.