No Single Point of Failure

Expectation. The building shall ensure that no resident is unable to enter their home due to the failure or unavailability of any single credential method, device, or system component.

Required.

• When the primary credential method is unavailable, an alternative method permits entry at every primary entry point without requiring another person's assistance.
• The alternative method does not depend on the same device, the same network, or the same system component as the primary method.
• The alternative method is usable by persons who do not own a smartphone, who have limited mobility or dexterity, or who cannot use the primary method for any reason.
• The alternative method and its location are described within the building's resident-facing digital interface and in materials provided at the start of occupancy.

Recommended.

• A resident whose credentials are entirely unavailable can reach a live response at any hour. Identity is confirmed through a method that does not require the missing credential. Entry is granted within a defined response time.
• The building offers credential options that accommodate religious observance of days without electronic device use, disability affecting touch or vision, and advanced age.

In practice.

A resident's phone is stolen. They return home at midnight, no staff on site. They enter using an alternative method — independent of the phone, independent of the network. They reach their unit. The next morning, they report the theft. The mobile credential is revoked. The alternative method continues to function.

A resident who does not own a smartphone moves in. They receive a credential that works at every entry point they are authorized to use. Their daily experience — speed, reliability, access to every zone — is identical to any other resident's.

A resident with arthritis cannot reliably operate a touchscreen. They use a large-format token that requires a single tap. It works at every entry point. It was offered alongside standard options when they moved in.

A resident observes a weekly day of rest during which they do not operate electronic devices. On that day they use a non-electronic method. Their access is uninterrupted.

Failure modes.

Displaced alternative. An alternative entry method exists but is located at a different entry point than the primary — a PIN pad at the service entrance, not the main lobby. The resident must walk around the building to use it. The alternative is technically available but practically inaccessible at the point of need.

Reduced-access alternative. The alternative method grants lobby entry but does not call the elevator or open the unit door. The resident is inside the building but cannot reach their home. The alternative covers one threshold but not the full path.

Enrollment catch-22. The building accommodates device-free entry, but the enrollment process for the alternative method requires a smartphone and an app download. A resident who needs the alternative because they lack a smartphone cannot enroll in it.

Test.

1. Remove the resident's primary device and all secondary digital credentials. Attempt entry using only the alternative method at every primary entry point. Confirm: entry succeeds at every point including the path to the unit.
2. Disable network connectivity. Attempt entry using the alternative method. Confirm: functions independently.
3. Review the resident-facing digital interface. Confirm: the alternative method is described with location and usage instructions.
4. Attempt entry using the alternative method with limited dexterity (simulated or actual). Confirm: the method is operable.