It is one of the intimidating charts for any building design professional: the psychrometric chart.
At first blush, the “psych chart” looks very complicated. There are layers of axes and curved reference lines. However, a closer examination will reveal that – at its essence – the chart is visually conveying the answers to two related questions:
- How much sensible (dry-bulb) heat is in the air? (See the green lines on chart above.)
- How much latent (moisture-related) heat is in the air? (See the cyan lines on chart above.)
Let’s unpack the psych chart one piece at a time and make sense of it all.