The Swiss civil protection minimum for shelter space is 1.0 m² per person. These figures keep people alive. They do not keep them functional, psychologically stable, or willing to remain in the shelter for the full period it was designed for.
The First 24 Hours
The initial period in a shelter is typically the most disorienting. The sequence of events that led to shelter entry was compressed and stressful. The outside situation is unclear. The shelter environment is unfamiliar.
What matters in this period is not comfort but control. Can occupants monitor the outside situation? Do they know how the ventilation system works? Is there a clear plan for the day's routine?
The first 24 hours are not primarily a habitability problem. They are a preparation and familiarity problem — and that problem must be solved before you ever enter the shelter.
Days Two to Five
By day two, the shelter is home for the foreseeable future and the occupants know it. This is when the design of the space begins to matter in ways that wall thickness does not.
- Light
- A shelter with no natural light relies entirely on artificial lighting for circadian regulation. In a uniformly lit space with no variation across the day, the day/night cycle degrades within days. The consequences: disrupted sleep, reduced cognitive performance, increased irritability. A lighting system that shifts from cooler white to warmer evening tones addresses this at moderate cost.
- Noise
- The shelter noise floor is high and continuous: the generator, fans, blast valves under test. In a monolithic concrete box with no soft furnishings, these sounds reflect and accumulate. The combined noise level without acoustic treatment is typically above what is acceptable for sleeping or sustained work.
- Space
- The 1.0 m² minimum was a survival standard. A standard single bed occupies approximately 1.0 m². A family of four at minimum specification has sleeping space but no space to be awake in. The planning standard used in long-duration institutional design is 4.0–6.0 m² per person.
Swiss Survival Minimum1.0 m² per person is sufficient to survive. It is the same footprint as a standard single bed — not a space to exist in for 14 days.
Days Six to Fourteen
By the second week, the routine has either been established or it has not. Several factors that were secondary in the first few days become significant:
- Children
- Children in a confined space without activity, outdoor time, or variety are not quietly patient. A shelter designed for an adult household and then occupied with young children under emergency conditions presents demands that were not in the design brief.
- Medical Requirements
- A member of the household who requires regular medication, has a chronic condition, or needs specific dietary provisions requires those provisions to have been stocked in advance and space to manage them. Medical provision is a design question, not an afterthought.
- Work
- A principal who must maintain communications and conduct secure calls during shelter occupancy needs acoustic separation, a defined workspace, reliable power, and a secure communications connection — none of which are standard in a 72-hour family shelter.
A shelter is used precisely once, under conditions that were not chosen. The question worth asking at design stage is not only whether it will protect — but whether it will be possible to stay in it for the period it was built for.
The Gap Between Adequate and Livable
A shelter that achieves the minimum specification is a genuine fallout shelter. But "survive" and "complete the designed occupancy duration in a functional state" are not the same outcome. The difference comes down to four design choices:
- Sufficient space per person for waking activity, not just sleeping
- A lighting system that supports circadian regulation
- Acoustic treatment that makes the noise environment tolerable
- Provisions designed for the actual household rather than a generic occupant profile
None of these change the structural specification. They change the design brief, the interior specification, and the shelter layout — and they must be established before the engineer starts drawing.
If you want an independent review of your shelter habitability brief, get in touch.
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