Purpose of a House: Desired Performance Outcomes
Define building performance by the outcomes a house must deliver for occupants and for the building (health, safety, durability, comfort, resilience). Establish priorities and tradeoffs before discussing assemblies or products.
How this fits in the series
Builds on: none — this is the starting point
Leads to: P2–P11
Core concepts and execution implications
- Performance is defined by outcomes, not components.
- Can list prioritized outcomes and use them to evaluate decisions.
- Outcomes can conflict under constraints.
- Can explicitly name tradeoffs rather than discovering them later.
- Technical decisions must trace back to occupant-relevant goals.
- Can explain "why" behind controls and assemblies.
Connections
- Performance framework: A — Desired Outcomes (A1 Safety through A9 Sustainability)
- Cross-series: A1 Affordability Overview (affordability as one of the nine outcomes)
- Explore in Performance Framework →
What good looks like
"Good" isn't one metric. We're aiming for a balanced scorecard of outcomes, and we'll make tradeoffs explicit instead of letting them surprise us later.
- Safety: fast threats (fire, CO, falls, burns, electrocution, unauthorized entry)
- Health: slower threats (contaminants via inhalation/ingestion/contact; chronic exposure)
- Comfort: thermal, humidity, acoustic, visual
- Durability: predictable, manageable aging
- Resilience: function through outages/failures/extreme events
- Affordability: acquisition, operation, maintenance, modification, deconstruction
- Function & usability
- Attractiveness
- Sustainability: GHG, resource efficiency, toxicity
Explore in PF: Safety (A1), Health (A2), Comfort (A3), Function (A4), Durability (A5), Resilience (A6), Affordability (A7), Attractiveness (A8), Sustainability (A9)
Where things go wrong
The most common real-world "failures" aren't dramatic collapses - they're complaints, callbacks, and slow damage. Below are patterns (roughly ordered by how often people encounter them), with a recognizable example under each. Examples:
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"The windy wall"
Moderate rain + strong wind → repeated wetting through small defects → staining, rot, callbacks.
Root issue: wind exposure underestimated
Field check: inspect wind-exposed walls for flashing continuity and drainage gap before cladding closes -
"Good roof, bad edge"
Roof field performs, but a transition (valley/skylight/chimney) leaks season after season.
Root issue: edge conditions ignored
Field check: walk every roof transition and verify flashing lap direction before roofing covers it -
"Drainage didn't matter… until it did"
Downspouts and grading look fine on day one → long-term splashback and wet foundation zone.
Root issue: site water management
Field check: verify grade slopes away from foundation and downspout discharge clears splash zone
Explore in PF: Safety (A1), Durability (A5), Envelope Failures (F3)