I can remember it well. It was one of the shortest conversations I've had with my wife. One hot summer night last year we were sat reading in bed, still sweating buckets after another sweltering July day. I glanced at the thermometer beside my bed, and it read 29.8C.

"Do you think we should get air-conditioning?" I ventured. "Absolutely", she barked back, in an instant.

Last summer was a record-breaker, with temperatures topping 40C at one point. All the weather geeks were warning us this sort of extreme would be the shape of things to come, and our south-facing bedroom was becoming a bit of a torture chamber.

We'd often toyed with the idea of spending a few hundred quid on a portable air-conditioner, but always hesitated because we'd convinced ourselves it was a lavish indulgence for something that would probably be used only three weeks of the year.

And, quite typically, the day our new Meaco MC Series 12000 unit arrived, the scorching temperatures dropped off.

But then August came and brought with it another burst of heat, putting us back into the 30s, and the big, expensive appliance we'd had sitting in the corner of our room for weeks really came into its own. We finally had a comfortable end to the summer. Do I regret owning a portable air-conditioner? Not on your nelly.

However, importantly, owning one for a year has been a real learning curve. In short, they're not as good as you might hope they are at cooling a room in a heatwave. On the flipside though, I'm not sure I could cope without one now.

Here's a full run-down of the pros and cons you need to consider before investing in one.

Why you absolutely shouldn't buy a portable air-conditioner

1. They're really not very good for the environment

The dirty little secret about air conditioning is that they consume huge amounts of electricity, which is obviously not a good thing, unless your house is powered by a huge solar array.

And they also emit hydrofluorocarbon refrigerants, which are more harmful to the atmosphere than carbon dioxide. Modern units, like my Meaco, are cleaner than older units, and a lot more efficient, but when we started using our air-conditioning system I chose to mitigate its impact by keeping my car at home and doing as many trips as I could on my bike. I'll be honest, I soon got bored of that, but it felt like the right thing to do at the time.

2. They're expensive to run

This will now seem obvious when you consider the above, but air-conditioning units work by exchanging heat, and that's a costly business. Be prepared for your bills to go up if you use one regularly.

Mine haven't been catastrophic, truth be told, but that's largely because we sold our hot tub in the same year. There's no getting around it, it will cost you money to run.

3. They're not very efficient

Because of the way portable, in-room air-conditioning systems work, they're always going to be fighting against themselves to some extent. A pipe expels the hot air from a room, but the unit will always be sitting in a hot space, and even if you've sealed up the outside vent really well, some hot air will inevitably get into the room you're trying to cool. There's a good reason why fully-installed air-conditioning systems live outside the building, rather than in the warm space.

4. They're bulky, heavy, ugly, awkward and noisy

They might be classed as "portable", but bear in mind they're big, heavy items. Mine weighs nearly 30kg. And then there's the exhaust hose. These are really cumbersome things to manage and, while they do come with an array of fixtures to ensure they fit well in your window aperture, some window types will work better than others. And that, incidentally, is if you can find somewhere by a window to position it. Not everyone will be able to do that.

During the vast majority of the year, if you don't have somewhere to store them, they'll have to live in your room and gather dust. And they do take up a lot of space.

Oh, and try sleeping with a noisy air-conditioning unit buzzing away. It is possible, and some might find it preferable to sweating all night, but I can't cope with it personally.

5. You have to remember to empty the water tank

All air-conditioning systems emit some water as they dehumidify the air, and portable air-conditioning systems usually retain this in a tank. Forget to empty this, and it spills out all over your carpet. Thankfully most will warn you before you get to this stage, but it's still a bit of a chore.

6. They only work in small spaces

Don't buy a portable air-conditioner thinking your whole house will feel cool, they're just not powerful enough. In a bedroom or living room, even quite a large one, they do make a difference, but don't go thinking you can just pop it in a hallway and enjoy blissful relief from the heat in every room, they're just not good enough.

Reasons why you absolutely should buy an air-conditioning system

1. They work

This is the most important reason to invest in a portable air-conditioner. Yes, there are plenty of caveats and there's lots of downsides to consider, but my south-facing bedroom has gone from being a 28C sweatbox to being consistently cooled to around 22C at the most, even during full-on heatwaves.

Walking into an air-conditioned room after you've mowed the lawn or you've been out on a run is absolutely wonderful. It's so good to have an escape from the heat, and you really can't put a price on a good night's sleep.

2. They're not as expensive as you might think

Sure, you could easily spend over £500 on a portable air conditioner, but there's really no need unless you live in a palace. You can find them for less than £200 if you shop around, and smaller units will do a decent job. Be realistic about the volume of air in your room, get your numbers right, aim to buy one that's slightly more powerful than you think you'll need, and buy it at the end of the season - now is probably a good time - and you should get a good deal on a perfectly capable appliance.

3. You'll use it more than you expect

One of the biggest reservations I had about owning a portable air-conditioner was the idea I'd only use it for a few weeks of the year. But the reality is, I've used it through most of the warmer months. Yes, we've had a bit of a rubbish summer, but sometimes, particularly when it's still and muggy outside, it's just nice to run the air-con for half an hour or so. It freshens the room up so quickly, and makes it a much more comfortable environment.

It's also worth remembering that the end of a hot spell doesn't mean the end of the internal heat. The house's bricks store warmth and release it slowly, so if a heatwave suddenly breaks down, you'll find you still need to cool the room for a while afterwards.

4. They can be moved from room to room

Yes, they're heavy and awkward to move, but if you need to cool another room during the day, you could plausibly move the air-con unit out of your bedroom for a while, and then back into the bedroom at the end of the day. Most of them are on casters.

So, for example, you could cool your home office or living room during a hot afternoon, and then when you're ready for bed, it could cool down your bedroom. Just make sure you can safely lift it and, of course, ensure you can find somewhere to vent the hot air away from.

5. You don't have to rely on manual controls

Most modern portable air-conditioners have schedulers and thermostats built in, so you don't need to manually switch it on and off. There are even a few which connect to apps, so you can control them remotely. You could also choose to add a peripheral device, like a SwitchBot button pusher, or an air-con controller to intelligently or remotely turn it on and off when the temperature reaches a certain point.

6. They're multi-purpose

Most portable air-conditioners can also work in reverse. So they can take the cold air out of a room, heat it, and send it back to you as warm air. Handy in winter? There are better ways to heat a room, to be honest, and you'll still need to vent the cold air out of a window, but it might be handy in some scenarios.

They also dehumidify a room, to an extent. This can mean laundry dries more quickly and in-built filters can remove some allergens, but if you want a dehumidifier, buy a dehumidifier. Air-con units will help, and it's a nice benefit, but bear in mind it's not their primary purpose.

Conclusion

Portable air-conditioning units will suit some people, but not others. It's important to make sure it will fit into your personal space properly, and there's a lot to consider before making the investment.

But if, like me, you're lucky enough to have space by a window for the vent, and if you can afford the added electricity cost, you honestly won't regret owning one.

I'd like to hope my Meaco will last at least five years or so, if not more, and if it ever does die a death, I'll head straight out to replace it.

And that hopefully sums up how happy I am to own one. It might be an indulgence, but it's a marvellous indulgence. I wish we'd bought one years ago.

To get your hands on the Meaco MC Series 12000 priced at £479 head here now.