applications / heat / study 09
Draft for review
Indoor thermal comfort
Comfort complaints are rarely about the thermostat. We simulate temperature, air movement and radiation inside a space to find why one desk is uncomfortable while the room average looks fine.
- Element
- Heat
- Indices
- PMV and PPD
- Standards
- ISO 7730
- Method
- CFD simulation
- Output
- Comfort and draught risk maps
The question
Why is this corner always uncomfortable?
A room controlled to a set point can still be uncomfortable. Cold air falling from a large window creates a draught at ankle height, warm air collects under a high ceiling, and a body seated near a glazed facade exchanges radiation with a surface that is far from air temperature.
None of this appears in a single sensor reading, which is why comfort complaints so often survive a system that is working exactly as specified.
What we simulate
The four quantities comfort depends on
The simulation resolves air temperature, air velocity, humidity and the radiant temperature of the surrounding surfaces, which are the physical inputs to a comfort assessment. Occupants and equipment are included as heat sources, and the facade is modelled with its real thermal behaviour.
From these we compute the predicted mean vote and the predicted percentage dissatisfied following ISO 7730, together with draught rate and vertical temperature difference, so the assessment is expressed in the terms the standard uses.
Where it is used
Difficult spaces and disputed ones
The study earns its place where the geometry is demanding, in atria, large open floors and heavily glazed spaces, and where a system has to be chosen between options that are hard to separate on paper.
It is also used after completion, when a building is delivered and the complaints do not match the design intent. Simulating the space as built usually shows the mechanism, which turns a dispute into a fix.
Other studies
Heat