Loads on Buildings & Occupants
Translate conditions into physical loads on the building and exposures for occupants, creating the bridge from context to technical requirements.
How this fits in the series
Builds on: P2 (environmental conditions & context)
Leads to: P4 (failure mechanisms & modes),
P5 (system interactions)
Core concepts and execution implications
- Loads are how conditions act on buildings.
- Can name dominant loads for common local scenarios.
- Occupant exposure matters as much as material stress.
- Can connect IAQ/comfort outcomes to load management.
- Reducing peak loads simplifies controls.
- Can identify strategies that reduce peak stress, not just treat symptoms.
Connections
- Performance framework: C — Loads/Demands (C1–C10), D — Occupant Exposures (D1–D5)
- Cross-series: A3 Permits, Fees & Taps (performance requirements drive permit complexity)
- Explore in Performance Framework →
Load categories
- Snow + wind: roof and lateral loads; drift/edge effects; exposure matters
- Soil movement: settlement, expansive soils, drainage effects
- Use loads: decks, stairs, guardrails—where failures become injuries
- Cold snaps: peak heating demand and comfort risk at the margins
- Solar + internal gains: overheating and glare (even in cold climates)
- Plug loads: real-world energy use that defeats "modeled" expectations
- Occupant moisture: showers, cooking, plants, humidifiers, laundry
- Events: parties, guests, wet gear—short peaks that matter
- Operation: how people actually use systems and openings
Explore in PF: Structural/Mechanical (C1), Thermal (C2), Moisture (C3), Air Quality (D1), Thermal (D2)
Where things go wrong
A lot of "mystery" comfort, durability, and cost problems come from the same root cause: the building was designed for one set of loads, and reality delivered another. Common patterns include comfort complaints (cold rooms, drafty zones, big temperature swings), moisture trouble from indoor humidity peaks, overheating from solar + internal gains, and energy surprises from plug loads and "always-on" devices. Examples:
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"The bonus room is always cold"
Peak load in an exposed zone is higher than expected → comfort complaints and endless tweaking.
Root issue: peak heating load underestimated
Field check: verify insulation continuity and air sealing at exposed zones; confirm supply airflow reaches room -
"It's efficient, but it overheats"
High solar gain + internal gains → summer discomfort despite good insulation.
Root issue: gains not managed (sun/occupants/appliances)
Field check: review glazing orientation and shading; check cooling capacity against south/west gains -
"Humidity spikes and musty smell"
Short, intense moisture events + limited ventilation strategy → recurring mustiness.
Root issue: moisture load not anticipated
Field check: confirm ventilation rate and dehumidification capacity; check exhaust at moisture sources
Explore in PF: Moisture (C3), Air Quality (D1), Thermal (D2)