How to reduce your heating bill

Stage 1

Drying the whole house out with a dehumidifier. Dry materials require less energy to heat up. Damp materials soak up energy.

[Evidence: Wear a dry cotton tee shirt and you feel warm. Wear the same tee shirt when it is damp and you will feel cooler].

The air is in contact with most things in the house. The temperature of everything it is in contact with will become the same temperature - in equilibrium.

Dending upon the amount of humidity there has been in the house will determine how much water will need to be removed. Typically a house that has condensation on the windows will produce 2 to 6ltrs of water in the first 24hrs. Then, over about a week or so, the amount of water being removed will reduce down to almost nothing. At that point it will be about 40 to 45%RH.

If, after say 2 weeks of having the dehumidifier running it is still pulling out a significant amount of moisture then further investigation is required.

Stage 2 - Further Investigation

Likely causes:

1. The extractors in the bathroom / shower room / ensuite / kitchen are not working (clogged up with lint and dust, or cooking fat)
2. Extractors not being used (Common issue in the summer when the light is not being used and the linked in switch to the extractor cannot work)
3. The rooms do not have extractors

Check if the cooker hood is an  extractor  or a  recirculator.  An extractor will have a vent that sends the humid air during cooking out of the building. A recirculator looks very similar, but the air is directed through a filter and back into the kitchen. No humidity is removed from the room though. The filters are designed to catch airborne fat.

Stage 3 - Drying out towels after bathing 

It is surprising how much water is dried off our bodies and from our hair after bathing. As an experiment weigh the towels before you use them. [It is easier to put them in a bowl and used the kitchen scales]. Note the dry weight in grams.

Then have your shower / bath. After drying yourself and hair, re-weigh the damp towels. Deduct the dry weight from the wet weight. 1 gram of water equals 1cc. There are 1,000cc in a litre.

Stage 4 - Mopping up the condensation

Using a high absorbant cloth, wipe down any condensation on the walls, and the shower and or bath. Wring the cloth out into a measuring jug.

Stage 5 - The assessment

Add the volume of water held in the towels to the water water in the measuring jug. All of that water will have become humidity within your home during the day and or night. It will have soaked into any soft furnishings such as the carpets, bed clothes, mattresses, sofas etc. The humid air will roll under furniture and condense. It will also be at a slightly higher pressure than inside your cupboards, wardrobes and drawers as it will be warmer. The humid air will eventually pass through any gaps however small as it is in a gaseous state.

When the humid air cools the humid air becomes liquid and soaks into anything that is porous. That is why clothes in drawers and wardrobes can have mould growing on them even if they are shut in a wardrobe or in closed drawers. Furniture that has a wood content is an ideal food for mould growth as it is mainly carbon in the form of sugars.

Clothes that are particularly vunerable to mould include cotton, hemp, jute, and leather. When fabric conditioners have been used regularly a coating remains on the fibres. That is what is being slowly released as the 'fresh smell' they advertise. It has a high carbon content so is more food for the mould to feed on.

So what has all this to do with how much it is costing me to heat my home?

Dry materials generally are easier to heat up than wet ones. Water requires a lot of energy to increase its temperature. Evidence: Put on a damp tee shirt and then swap it for a dry one. The dry one will feel warmer as your body can easily heat the air between the fabric and your skin. The damp tee shirt will require more body heat to heat up the added moisture so you feel cooler. A wet tee shirt will require far more body heat.

The same as heating your home. A damp home will require far more energy just to heat the extra moisture.

What is the solution?

Remove as much of the additional moisture. That is the wet towels from bathing, drying washing indoors, and using extractor fans when cooking and in the bathroom / shower room. (Ideally with a 30minute over run).

It isn't worth putting an extractor on when boiling water in a kettle. However, using several pots and saucepans on a hob, or frying on a hob is worth using the extractor. The process of cooking includes freeing water molecules plus fats into the air. 'Oooh - that smells good!' can only happen if your sensors have contacted the atomised fats from what is cooking. The smell of freshly baked bread, or coffee wafting around the room. It is only the atomised fats and particulates that enable to smell to occur.

Humidity in the air is relative to dry air. It is measured as a percentage - such as 45%RH. That means the air has 45% more moisture than dry air. We need moisture in the air.

Plants and animals need moisture. Even materials require some moisture. So we are not trying to go down to zero humidity. General day to day relative humidity should be about 40%RH. It can peak occasionally up to around 80%RH when someone has just had a shower or bath. However, it should go back to around 40%RH again reasonably quickly. That is the reason for taking the mositure out of the air.

What happens if the RH is lower than 30%RH? Your skin and eyes will notice it. Your skin will feel itchy and may start flaking as it is too dry. Your eyes naturally are lubricated every blink. The liquid wipes the ultra small particulates down into your tear ducts. Pollens, dust, airbourne spores and so on. The liquid also lubricates the surface under your eye lids. Very low RH and your eyes may feel tired and sore.

Relative humidity also reduces static electricity by constantly conducting it to Earth via the moisture. A really dry carpet made from wool and nylon, or just man-made fibres when in contact with other similar materials such as sock and tights etc.

As they contact, the atoms / molecules collide and an electric charge is produced. Very small, but can build up if not constantly being Earthed. The consequence is when a person touches an item that can discharge the static electricity, they can get a painful electric shock.

If your home is going to be vacated most of the day it is likely to be made secure with locked doors and windows. To reduce the RH from bathing etc. and parhaps drying washing indoors (a problem if you are in a multi-storey housing especially). Use a dehumidifier with a laundry mode and timer.

Place the machine in the kitchen and use a clothes horse to drape wet towels or washing. The machine should be placed as recommended by the manufacturer so it removes the moisture into liquid form. When the RH in the room has reduced to about 40%RH the machine is designed to automatically turn off so it won't over dry the air.

Ideally, leave all doors to the rooms slightly open so the air can freely move about. When moisture evaporates into the air it diffuses. Diffusion of the H₂O molecules will continue until eventually all of the air has an equal amount. The dehumidifier will be taking moisture continually so the whole dwelling will gradually be drying out.

[When the outside air has a high Relative Humidity (55%RH) as today 15th August 2025, the diffusion will increase the RH in your home. Using a dehumidifier is unlikely to achieve any useful purpose until the outside air RH is lower].