Beta 6
Now with concrete, vehicle and home temps and profiles
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// These are real-world physics values — don't change them unless you
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// have a peer-reviewed reason. They're used by calcTmrt() below to
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// work out how much heat your skin actually absorbs from the sun.
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// SIGMA — Stefan–Boltzmann constant (radiates heat)
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// EPSILON_P — emissivity of human skin (~0.97)
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// A_K — short-wave absorption coefficient for clothing
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// ALBEDO_GRASS — how much sun grass reflects back at you (23%)
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// SIGMA — Stefan–Boltzmann constant (radiates heat)
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// EPSILON_P — emissivity of human skin (~0.97)
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// A_K — short-wave absorption coefficient for clothing
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// ALBEDO_GRASS — how much sun grass reflects back at you (23%)
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// ALBEDO_CONCRETE — how much sun concrete reflects back (30%)
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// Concrete absorbs more net solar than grass and has
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// no evaporative cooling, so its surface runs hot.
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// ═══════════════════════════════════════════════════════════════════
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export const SIGMA = 5.670374419e-8;
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export const EPSILON_P = 0.97;
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export const A_K = 0.7;
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export const ALBEDO_GRASS = 0.23;
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export const SIGMA = 5.670374419e-8;
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export const EPSILON_P = 0.97;
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export const A_K = 0.7;
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export const ALBEDO_GRASS = 0.23;
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export const ALBEDO_CONCRETE = 0.30;
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// ═══════════════════════════════════════════════════════════════════
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// CONCRETE SURFACE TEMPERATURE (Urban profile)
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// ───────────────────────────────────────────────────────────────────
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// Estimates the surface temperature of exposed concrete using a
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// simplified energy-balance approach:
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// • Absorbed solar = globalRad × (1 − albedo)
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// • No latent heat (no evaporation — concrete is dry)
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// • Convective loss to air proportional to wind speed
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// • Result is clamped to a physically plausible range
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//
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// This is what matters for contact heat stress in cities — the UTCI
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// standard uses grass, which runs ~5–15 °C cooler than urban concrete
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// on a sunny day because grass sweats (transpires).
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// ═══════════════════════════════════════════════════════════════════
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export function calcConcreteTemp(Ta, globalRad, windSpeed) {
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if (globalRad == null || Ta == null) return null;
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const absorbed = globalRad * (1 - ALBEDO_CONCRETE); // W/m²
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// Convective heat transfer coefficient: ~5 W/m²K still air, rises with wind
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const hc = 5 + 4.5 * Math.sqrt(Math.max(windSpeed || 0, 0));
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// Surface temp: Ta + solar gain / convective loss
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const Ts = Ta + absorbed / hc;
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// Clamp: can't be cooler than air, cap at 85 °C (melting asphalt territory)
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return Math.max(Ta, Math.min(Ts, 85));
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}
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// ═══════════════════════════════════════════════════════════════════
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// UK HOUSE INDOOR TEMPERATURE (windows closed, no active cooling)
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// ───────────────────────────────────────────────────────────────────
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// Estimates the ambient indoor air temperature of a typical UK brick
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// house with windows closed and no air conditioning.
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//
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// Two heat pathways are modelled:
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//
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// 1. WALL CONDUCTION
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// Heat conducts through brick cavity walls and roof. UK Part L
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// compliant walls have a U-value around 0.28–0.45 W/m²K; older
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// solid-brick stock runs higher. A representative mid-stock value
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// is used. This drives a slow, steady heat transfer proportional
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// to the difference between outdoor and indoor air temperature.
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//
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// 2. WINDOW SOLAR GAIN
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// A typical UK semi has ~15–18% glazing ratio. Solar energy
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// transmits through glass, is absorbed by floors and furniture,
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// and heats the indoor air. Gain is averaged across orientations
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// (not all windows face south). Diffuse radiation contributes
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// regardless of sun angle.
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//
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// THERMAL LAG
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// Brick and concrete have high thermal mass — the house responds
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// slowly to outdoor temperature swings. This function takes a
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// weighted average of the current hour's heat load and the
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// previous few hours', giving the characteristic lag where indoor
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// temperature peaks 2–4 hours after the outdoor peak.
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// Call calcIndoorTempPass() on the full hourly arrays after
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// building rows — it returns a per-hour indoor temp array.
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//
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// No mechanical cooling. Minimal infiltration (windows closed).
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// Internal heat gains (people, appliances) are not modelled.
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//
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// Colour thresholds:
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// < 20 °C — cool, may need heating
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// 20–26 °C — comfortable
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// 26–32 °C — warm; WHO heatwave advisory threshold for sleeping
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// > 32 °C — hot; risk for elderly and vulnerable occupants
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// ═══════════════════════════════════════════════════════════════════
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// Single-hour instantaneous heat load (W/m² effective, indoor side).
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// Used internally by calcIndoorTempPass — not exported.
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function _houseHeatLoad(Ta, globalRad, solElev) {
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// Wall + roof conduction: U-value ~0.35 W/m²K × effective envelope area ratio
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// We express as a gain-per-degree-delta — applied against Ti later in the pass.
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// (See calcIndoorTempPass for how this feeds the lag model.)
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// Window solar gain: glazing ratio 0.16, g-value 0.63 (standard double glazing),
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// averaged across orientations (0.5 factor — not all windows face the sun).
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const glazingRatio = 0.16;
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const gValue = 0.63;
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const orientFactor = 0.50;
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const solarGain = globalRad * glazingRatio * gValue * orientFactor;
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return { conductionDelta: Ta, solarGain };
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}
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// Two-pass function: call with the full arrays of hourly Ta and globalRad.
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// Returns an array of indoor temperatures, one per hour.
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export function calcIndoorTempPass(TaArr, globArr, elevArr) {
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const n = TaArr.length;
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const result = new Array(n);
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// Thermal resistance of the building envelope (°C per W/m² of heat load)
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// Lower = faster response to outdoor changes. UK brick mid-stock ~0.45.
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const uWall = 0.35; // W/m²K effective wall U-value
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// Thermal mass time constant: heavier = longer lag.
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// ~4 h lag for typical UK brick semi (expressed as exponential decay weight).
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const lagHours = 4;
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const alpha = 1 - Math.exp(-1 / lagHours); // per-hour blending weight
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// Seed indoor temp to first outdoor temp
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let Ti = TaArr[0] ?? 15;
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for (let i = 0; i < n; i++) {
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const Ta = TaArr[i] ?? Ti;
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const glob = globArr[i] ?? 0;
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const solElev = elevArr[i] ?? 0;
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// Solar gain through windows (W/m² effective)
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const glazingRatio = 0.16;
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const gValue = 0.63;
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const orientFactor = 0.50;
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const solarGain = glob * glazingRatio * gValue * orientFactor;
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// Conductive heat flow through walls: proportional to (Ta - Ti)
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// uWall drives how quickly the indoor temp chases outdoor temp.
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const conductionGain = uWall * (Ta - Ti);
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// Target indoor temp this hour if there were no thermal mass:
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// Ti_instant = Ti + conduction + solar load / heat capacity proxy
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// heatCap proxy: how many degrees does 1 W/m² raise the indoor air?
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// For a typical 90 m² house, ~0.15 °C per W/m² effective.
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const heatCapProxy = 0.15;
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const Ti_instant = Ti + (conductionGain + solarGain) * heatCapProxy;
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// Apply thermal lag: blend toward Ti_instant slowly
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Ti = Ti + alpha * (Ti_instant - Ti);
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// Can't be colder than outdoor (house doesn't actively cool)
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// Cap at 55 °C (physically implausible above this for a house interior)
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result[i] = Math.max(Math.min(Ti, 55), Math.min(Ta, Ti));
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}
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return result;
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}
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// ═══════════════════════════════════════════════════════════════════
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// VEHICLE INTERIOR CABIN TEMPERATURE (seated occupant, not in sunbeam)
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// ───────────────────────────────────────────────────────────────────
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// Models the ambient cabin air temperature experienced by an occupant
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// seated out of direct sunlight inside a sealed, parked vehicle.
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// Two heat sources are combined:
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//
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// 1. PANEL CONDUCTION
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// Aluminium body panels absorb solar radiation and conduct heat
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// into the cabin. Albedo ~0.25 (mid-point for typical mixed-colour
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// fleet; dark paint ~0.10, silver/white ~0.40).
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// Panel surface temp → conductive gain into cabin air.
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//
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// 2. SIDE-WINDOW GLAZING GAIN (sun-angle dependent)
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// When solar elevation is between ~10° and ~60°, the sun's rays
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// cut through the side glass at an angle that allows significant
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// transmission into the cabin (rather than hitting the roof or
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// reflecting off at a shallow angle). This warms the cabin air
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// but the occupant is modelled as NOT sitting in the beam —
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// so it adds to ambient cabin temp, not direct radiant load.
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// Above 60° the sun mostly hits the roof; below 10° it reflects.
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//
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// Wind is ignored (vehicle is sealed). No evaporative cooling.
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// Steady-state reached after ~45–60 min of parking.
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//
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// Colour thresholds in the table:
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// < 35 °C — warm but tolerable for short periods
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// 35–45 °C — dangerous for children/pets (hyperthermia risk)
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// > 45 °C — potentially fatal within minutes
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// ═══════════════════════════════════════════════════════════════════
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export function calcVehicleInteriorTemp(Ta, globalRad, solElev) {
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if (globalRad == null || Ta == null) return null;
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// ── 1. Panel conduction ──────────────────────────────────────────
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const albedoPanel = 0.25; // typical mixed fleet
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const panelAbsorbed = globalRad * (1 - albedoPanel); // W/m² absorbed by bodywork
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// Panel surface temp: absorbed solar / convective loss to outside air
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// hOut ~10 W/m²K (light breeze over panel surface even when parked)
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const hOut = 10;
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const panelSurfaceTemp = Ta + panelAbsorbed / hOut;
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// Conductive gain into cabin: panel-to-cabin air, ~4 W/m²K through metal + trim
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const hCabin = 4;
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const conductionGain = hCabin * (panelSurfaceTemp - Ta); // W/m²
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// ── 2. Side-window glazing gain (angle-dependent) ─────────────────
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// Glazing transmission for auto glass ~0.70
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const tau = 0.70;
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let glazingGain = 0;
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if (solElev != null && solElev > 10 && solElev < 60) {
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// Scale factor: peaks around 30–40° elevation (sun cuts squarely
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// through side glass), tapers off toward 10° (shallow/reflected)
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// and 60° (sun increasingly hitting roof not side glass).
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// Use a simple tent function peaking at 35°.
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const peak = 35;
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const halfWidth = 25; // degrees either side
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const factor = Math.max(0, 1 - Math.abs(solElev - peak) / halfWidth);
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// Diffuse radiation also enters through glass regardless of angle
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glazingGain = tau * globalRad * factor * 0.5; // occupant not in beam → 50% ambient
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} else {
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// Outside the side-window zone: diffuse only (scattered sky light)
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glazingGain = tau * (globalRad * 0.15); // ~15% diffuse fraction
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}
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// ── Combine into cabin air temperature ───────────────────────────
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// Total heat input per m² of cabin surface
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const totalGain = conductionGain + glazingGain;
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// Cabin heat loss: poor natural ventilation in sealed car ~2.0 W/m²K
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const hCabinLoss = 2.0;
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const Ti = Ta + totalGain / hCabinLoss;
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// Clamp: can't be cooler than outside air; physical cap at 90 °C
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return Math.max(Ta, Math.min(Ti, 90));
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}
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// Vapour pressure (Magnus → hPa)
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export function vaporPressureHpa(Ta, RH) {
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