Why does a room at 19 degs feel colder on a cold dark night?

[Vortex2]

Why does a room at 19 degs feel colder on a cold dark night?

[clv101]

Is the humidity the same? That has a bearing on how it feels.

Even though you say the room is at the same 19 degrees, is it really? All the same? What if you place the thermometer on the floor, might it actually be a degree or two cooler?

When it's 19C inside and outside, there's a steady thermal state. When it's 19C inside but 0C outside there's a lot more going on, skin temperatures of floors, walls and especially doors and windows will be a little lower, that could set up convection in the air not present in the summer. Having slabs of glass at 16C rather than 19C will also have an impact on radiation.

[Little John]

Why does a room at 19 degs feel colder on a cold dark night?

I wonder, if the temperature is the same in the room at night, the reason it may feel colder is because the human body is less able to maintain its own temperature as sleep approaches. Thus, more ambient heat from outside the body is required to assist in that. Just guessing.

The alternative is that you are imagining it is colder.

[adam2]

I have not noticed that a room at say 19 degrees feels any colder at night than in daylight.

I have however observed that a room at 19 degrees feels cooler on a cold day than in milder weather. I can think of at least three reasons for this.

Firstly if it is very cold outside, then a room heated to 19 degrees is likely to have a very low humidity, this promotes evaporation of perspiration and makes it feel colder.
A room that is at 19 degrees without any heating in moderately cool weather will be more humid and therefore warmer feeling than the same room heated to 19 degrees when it is frosty outside.

Secondly, in prolonged cold weather, the brick or stone walls of a room may become very cold. A suitable heating appliance will soon raise the AIR temperature to 19 degrees, but the cold walls promote loss of body heat by radiation and the room therefore tends to feel cold.

Finally, if the living room be heated to 19 degrees in severe weather, then other rooms might be colder. Leaving the 19 degree room to relieve oneself, or answer the front door, or fetch food and drink, could result in one becoming chilled in these other rooms.
In moderately cool weather when the living room is naturally at 19 degrees without any heating, then other rooms will probably be at about the same temperature, and therefore one cant become chilled when visiting these other rooms.

[clv101]

How is your new house performing in the cold, Vortex? We've had two frosty mornings last week, downstairs temperature around 16C first thing. Not felt the need for space heating yet though, back up to ~18C by afternoon thanks to cooking, solar gain, body heat etc.

[kenneal - lagger]

Why does a room at 19 degs feel colder on a cold dark night?

The most likely cause is, as has been said above, a cooler inner skin of outside walls and window surfaces. These will absorb radiation from the body and leave you feeling colder. If those surfaces are warmer they will reradiate any radiation that they receive so the body feels warmer.

Another possible cause is draughts. Moving air in a room will take heat from your body faster than still air.

So check the inside surface temperature of the outside walls to see if you have any cold spots and check for cold draughts. Both of these can be done with a hired infra-red camera. Cold draughts will show up as blue lines around the edges of windows and opening casements.

[Vortex2]

How is your new house performing in the cold, Vortex? We've had two frosty mornings last week, downstairs temperature around 16C first thing. Not felt the need for space heating yet though, back up to ~18C by afternoon thanks to cooking, solar gain, body heat etc.

We have a 'Kombi' air & water heater based on an air source heat pump.

Tricky to assess performance in some ways : the unit can heat EITHER water OR AIR. You have to set the 'preference' for the mode. You cannot however program a blended solution where heating and air heating water are automatically 'multiplexed'.

Our solution is to have air heating prioritised during the day BUT overnight we program the temperature 5 degrees down to around 16 C until 5AM as we like a cool bedroom. This has the advantage of freeing up the compressor to heat water overnight so we can have a hot shower in the morning.

So the main room is maybe at 16 - 18 first thing, by choice. (We can't zone the temps per room)

(We can optionally program an immersion heater to come on if the tank gets too cold)

[Vortex2]

Re cold/hot rooms.

I have used a handheld IR remote thermometer ... 20 degs all round tonight, including floor .. yet I feel cold.

I suspect that being ancient my internal thermal regulator is bust (they fail over the age of 50) - or it could be a medical issue when I am tired (I have MS).

[Little John]

Re cold/hot rooms.

I have used a handheld IR remote thermometer ... 20 degs all round tonight, including floor .. yet I feel cold.

I suspect that being ancient my internal thermal regulator is bust (they fail over the age of 50) - or it could be a medical issue when I am tired (I have MS).

If it feels cold, put an extra jumper on or turn the heating up mate. Sod what the dial on the wall says. You body does not lie.

[adam2]

20 degrees IS a bit chilly for most people under most conditions if they are sedentary.
20 degrees should be fine if somewhat active, but is bit chilly if simply sitting and reading or using a PC.

I would aim for a temperature of about 20 degrees if somewhat active, or 22 degrees if sedentary.
This presumes normal winter indoor clothing and normal health.
Socks with slippers or shoes.
Thick trousers or lightweight trousers and long underpants.
Thick long sleeved shirt with either a vest under it, or a pullover over it.

As mentioned previously, I favour a Cornish smock for indoor winter wear.
.https://thesmockshop.com/
I have several, they are 100% cotton so more comfortable than poly-anything, and if purchased in a large enough size they permit of warm clothing underneath.
Almost indestructible in normal use.
The above firm are actual makers of the smocks and can make custom sizes to order.
I confirm that I have no connection with the above firm. Alternatives exist, but most are retailers not manufacturers.

[Vortex2]

20 degrees IS a bit chilly for most people under most conditions if they are sedentary.
20 degrees should be fine if somewhat active, but is bit chilly if simply sitting and reading or using a PC.

I would aim for a temperature of about 20 degrees if somewhat active, or 22 degrees if sedentary.
This presumes normal winter indoor clothing and normal health.

Hmm ... could be right - I accidentally had the temp set to 22 C for a while ... no problems whatsoever.

[kenneal - lagger]

We are quite comfortable at 18C or 19C with the wood burner providing radiant heat in the living room or the under floor heating on. We usually go with just the woodburner heating the living room and keeping the chill off the rest of the house rather than trying to heat the whole house with a woodburning cooker/boiler and underfloor heating.

Below 18C and the nose starts to feel cold even with heavy trousers and three layers, T shirt, shirt and fleece.

[adam2]

A neighbour complained that they felt cold when the thermometer showed 23 degrees.
That was because the thermometer was placed near a heat source ! If placed more sensibly, it showed 19 degrees.

They have only just moved into the house, and have sought my advice re heating/fuel/energy.
The house LOOKS like a barn conversion but is actually newish build and well insulated.

[kenneal - lagger]

New build houses are notorious for not achieving the insulation levels they are designed to. This is usually because the insulation is not fitted correctly or the air tightness levels designed in are not achieved in building or both. If the house is dry lined and the perps in the blockwork, the vertical joints between blocks, have not been filled properly, a common occurrence as brickies are on piecework, a howling gale can come through at skirting level. An infra red camera can pick this up.

[adam2]

The house in question looks well built, it was built in about 1980 by an experienced builder for his own use and only sold recently after he suffered serious illness.

External walls have exposed oak frames with brick infill. These walls are solid and very thick. Brick on the inside and outside with an intermediate layer of thermal insulating blocks.

I suspect that the central heating is not working correctly. It was known to be defective when the house was sold.
New owner has replaced the oil fired boiler, but I suspect other faults.

Most unusually for the UK this property has full central air conditioning, which works fine in cooling mode but not properly in heating mode.