Reddit reviews Infrared Forehead Thermometer, Non-Contact Forehead Thermometer for Adult, Kids, Baby, Accurate Instant Readings No Touch Infrared Thermometer for Face, Ear, Body (Purple 2)

Do you mean in the case of a bolometer like this? The laser does not measure the temperature, it is just used to align the IR sensor visually.

Mold is a really complicated issue, and usually it's both an issue with the building (responsibility of the landlord) and the tenant's use of the building (responsibility of the tenant). Yes, the landlord has to help you - but they will argue as much as possible that it's entirely your fault (through incorrect use of the building) in order not to have to do anything. Since the mold is primarily damaging to your health, however, it would be in your best interests to better understand the causes - that way, you can either change your behaviour, or have solid evidence that the landlord needs to do something to the building.

Yes, sadly, this often means a fair amount of work for you.

The TL;DR for mold is that mold grows whenever the relative humidity at the surface of the wall (or just below the surface) is at or near saturation (i.e. around 80-100%). You first need to determine where the humidity is coming from.

• Is it coming from the air in the room? Bathrooms are prime candidates for mold, as showering increases the humidity content of the air to near saturation. Buy a hygrometer (example - there are plenty of models on the market) and watch the relative humidity of the air. Whenever it exceeds 60%, open the window (assuming that the air outside isn't even more humid than the air inside - an inside-outside thermometer/hygrometer is useful here) until it drops below 60%. Those hygrometers in general are super useful for telling you when and how much to open your windows to ventilate - I've got one in every room in my house.
  
• Is it coming through the wall? Even if you keep the room nice and dry, perhaps the wall (is it an exterior wall?) isn't watertight, and water is seeping in from the outside. You can't determine this directly, but if the air in the room is always below 60% humidity and the mold keeps growing, this is a strong indication of an issue with the building itself (a leaky wall).
  
  You then need to determine why that particular spot on the wall is a problem.
  
  
• Why is the wall cold? You'll notice that mold needs 80-100% relative humidity, while I was aiming for 60% in the ambient air. The reason is that, if the wall is colder than the air temperature, then the relative humidity increases as you get closer to the wall (cold air can hold less water vapour than warm air). You'll want to measure the temperature of the wall - an infrared thermometer (example - again, there are plenty of models available) is good for this. Record the wall temperature throughout the year - see if there is a spot that's much colder than the rest, and how it varies with the outside temperature.
  
  The wall could be cold due to:
  
  
• An external reason, e.g. a lack of insulation in the wall (a so-called Kältebrücke)), or
  
• An internal reason: You leaving the window half-open (auf Kipp) for too long, and so the cold outside air is cooling the wall just above the window (which is why you should never leave your windows half-open for prolonged periods of time in winter).
  
  Once you've collected enough data to fend off the immediate "you just need to ventilate more" reaction, go to your landlord and demand that he send a Gutachter (surveyor / expert) to determine the cause. This will take a while - the Gutachter will probably need to take many measurements throughout the year to determine the cause of the mold.
  
  If your landlord refuses to send a Gutachter, then you should consult with a lawyer (or join the local Mieterbund) to see whether you can unilaterally reduce the rent you pay until the mold problem is fixed. Here is an introduction - reducing the rent is a way to pressure your landlord into doing something about the problem.
  
  > I think the windos are letting water seep in from outside for example. When it's humid outside the windows have water drops running down them in the inside.
  
  This is interesting. It could be that your window doesn't seal (so it's letting humidity in from the outside), or that your window doesn't insulate very well (so the glass pane is simply cold, causing the humidity present in the room to condense on the pane). Observe and record this when it happens - temperature and humidity inside and outside. You're trying to see if there is a pattern, and whether it depends on outside temperature or rainfall. Honestly, most of the time it's just a lack of insulation in the pane (combined with a high internal humidity) - which is not a problem with the building.
  
  > No extractor fans or vents in the kitchen or bathroom.
  
  You don't need it if you have an exterior window.
  
  > The windows seem to be constantly steamed up and when we turn the heat up the water drips off them.
  
  This isn't causing mold per se, but it's probably an indication that the humidity inside the apartment is far too high. Use the hygrometers (see above) to meausure it, and strategically open your windows to lower it:
  
  
• Open them for a brief period (5-10 minutes) at least twice a day in the winter, preferably when the outside air is cold and dry.
  
• Don't open them if it's raining outside.
  
• Never leave them half-open for a prolonged period of time (exception: at night in summer, unless it's raining - you neither want cold winter air, nor humid summer air from constantly entering your apartment).
  
• In the summer, only open them (for a little longer - 15-20 minutes) if the outside air is dry and cooler - e.g. in the morning and evening, unless it's been raining.
  
• If possible, open windows on both sides of your apartment at the same time - this drastically cuts down on the time necessary to replace the humid air inside the apartment.
  
  Worst case, buy a dehumidifier - although note that they use a ton of electricity to run, but they're a good last-ditch brute-force solution for getting your humidity levels down.
  
  Good luck! :)