Everyday Indoor Comfort Situations and Decisions
Permanently changing conditions
This guide presents some simple actions that could be taken in various indoor situations. Based on rules and preferences, these decisions may be taken in a different way or at a different time but they offer a good starting point for considering what is to be done and why.
Keep in mind that attempting to change indoor conditions to reach a specific comfort level requires time and this is major reason that decisions should be made preemptively rather than on the spot. One major advantage of preemptive decisions is that they create less stress on people and equipment and also require less energy consumption.
Default target
When in doubt about any specific approach, always target the lowest humidity you can reliably achieve using natural or forced ventilation, without leading to serious personal discomfort due to it. Even if the temperature may be higher or lower than desired, on the moment, the situation is easily manageable.
Keep in mind that dry air is the easiest to cool or dry and that just about any human activity increases humidity. Indoor air temperature is also, generally, self regulated in the space, by layout, objects and occupiers, in less than 1 hour, with no external intervention.
| Indoor Temperature | Indoor Relative Humidity | Comment |
|---|---|---|
| 21-26 Celsius Degrees | 30%-35% | Too dry for some persons |
| 21-26 Celsius Degrees | 35%-40% | Stop humidity control measures |
| 21-26 Celsius Degrees | 40%-55% | Comfort area for most persons |
| 21-26 Celsius Degrees | 55%-60% | Start humidity control measures |
| 21-26 Celsius Degrees | 60%-65% | Too humid for some persons |
| 21-26 Celsius Degrees | 70%-85% | Humidity may be harmful |
In slightly drier air or body feels more comfortable both when experiencing warm and chill, so targeting humidity and after that temperature has major benefits in lowering energy consumption since both cooling and heating require energy.
Dehumidifying is automatically carried out when cooling due to the inherent way of operation for air conditioning systems! Relative humidity is slightly reduced when heating an interior space but it is costlier than simply dehumidifying air by itself.
Even values as low as 25-40% relative humidity are bearable when outside air enters an indoor area. If you have any doubts about this circumstance, consider that you can perfectly accept this situation when walking outdoors unless there are some severe respiratory illness manifesting.
Slowly increasing humidity
Relative humidity should be ideally kept below 65%. When values reach 60% some preemptive measures should be considered.
In this context, current relative humidity reading should be less than 1% higher every 1 or 2 minutes. In larger rooms, this process is slower than in smaller rooms.
Natural ventilation by opening a window should be considered. During rain or humid times, as seen on local weather stations or on the internet, dehumidifiers or air conditioning devices should be started with a target of 50% humidity.
Quickly increasing humidity
Particular to bathroom and kitchens, before reaching 55% relative humidity preemptive measures should be considered. Keep in mind that hot showers, baths, clothing and bed accessories drying as well as boiling water generate massive amount of humid air that is very hard to counter.
In this context, current relative humidity reading should be 2-3% higher every 1 or 2 minutes. In larger rooms, this process is slower than in smaller rooms.
Natural ventilation by opening a window should be considered. During rain or humid times, as seen on local weather stations or on the internet, dehumidifiers or air conditioning devices should be started with a target of 40% humidity or ran continuously until reaching this value.
To reduce the impact of humidity that can be very difficult to keep in check, it may be useful to start dehumidifying on continuous mode around a half an hour before starting any intense activity in bathrooms and kitchens and keeping it on around a half or an hour after such activity is finished to reduce lingering effects.
Slowly increasing temperatures while ventilating
Slowly increasing temperatures do not have a major adverse effect unless accompanied by an increase in relative humidity of the indoor space, as can be the case in some summer days.
In this context, current temperature reading should be 0.5 Celsius degree higher than 1 or 2 minutes ago. In larger rooms, this process is slower than in smaller rooms.
If humidity outside is high the risk of increasing it also on the inside means that ventilation should stop. Note that if the inside temperature is lower than the one on the outside, humidity will naturally increase when outside admitted air gets cooler.
Slowly dropping temperatures while ventilating
Slowly dropping temperatures do not have a major adverse effect, even if they are slightly discomfortable on the spot. When humidity seems to drop less quickly than temperature, the effect of natural ventilation is reduced but still present until temperature begins to drop less quickly.
In this context, current temperature reading should be 0.5 Celsius degree lower than 1 or 2 minutes ago. In larger rooms, this process is slower than in smaller rooms.
When both temperature and humidity drops less quickly, air circulation is also slower and natural ventilation, by opening windows, tends to have less of an effect on indoor air quality.
Note that forced ventilation can be much more effective at improving indoor air quality even if the temperature and humidity does not drop much from the initial state.
Quickly dropping temperatures while ventilating
Such a condition signals that air circulation is best at this moment and it reinforces the benefits of replacing indoor air with the one outside through open windows.
In this context, current temperature reading should be 0.5 Celsius degree higher than 1 or 2 minutes ago. In larger rooms, this process is slower than in smaller rooms.
Care should be taken so that persons can cope with such a momentary condition. If this is not the case, partition air exchange should be considered, meaning that ventilation should be reduced in certain areas and kept at the same strong rates in unoccupied areas that do not interact with these occupied spaces.
Slowly dropping day temperatures
Trends toward lower temperatures may lead to discomfort. A specific value should be set at which remedial action should be taken, particularly if the air is not currently warmer or cooler air conditioned.
In this context, current temperature reading should be 0.5 to 1 Celsius degree lower than 1 day ago. Most buildings take at least 10 hours to respond to major outside weather changes.
A set temperature should be established by accord that would result in starting indoor heating equipment at a specific power output.
If heating is already started, adjustments proportional to the difference between actual and desired temperature should be applied.
Slowly increasing day temperatures
Trends toward higher temperatures may lead to discomfort. A specific value should be set at which remedial action should be taken, particularly if the air is not currently warmed or cooled using air conditioning equipment.
In this context, current temperature reading should be 0.5 to 1 Celsius degree higher than 1 or 2 minutes ago. Most buildings take at least 10 hours to respond to major outside weather changes.
A set intervention temperature should be established by accord that would result in starting either natural, forced ventilation or air cooling by using conditioning devices. Sometimes, with warmer and humid exterior air the only choice is to keep out air circulation in warmer areas and force it through in nearby cooler rooms or shaded areas.
Shading an area under direct sunlight can alleviate some of the sun's heating impact and exterior solutions are much more effective than interior ones.
If cooling is already started, adjustments proportional to the difference between actual and desired temperature should be applied.