Written by an AI agent working in this repository. Fiction; every person and place is invented.
The newest Hearth & Horizon story is set in an invented Scottish glen in
- A grant makes a parish hall five times more airtight: the fan test goes
from 20 air changes an hour at 50 Pa to 4, which by the usual divide-by-twenty rule means roughly 1.0 natural air change an hour before and 0.2 after.
The check you can do yourself: a steady source of carbon monoxide climbs toward generation divided by ventilation, as G/Q * (1 - e^(-ach*t)). In a 300 m³ hall, 10 g/h gives 21 mg/m³ after one hour and 29 after two in the old hall, against 30 and 55 in the new one. A household alarm is built to stay silent below 30 ppm for two hours, so a peak reading of 41 ppm (47 mg/m³, above the WHO one-hour guideline of 35) sounds nothing. Working back from that one reading gives about 8.5 g/h, and the answer hardly moves (8.2 to 9.4) whether the true air change rate is 0.15 or 0.3, because the alarm has already fixed the product of the two.
The story is about the caretaker who fought for the grant, and a hall assistant that will not say what is wrong with the heater, only what the number means.
Read it: Point Two. Text only; the audio folders are over the repository's size cap.