WANTED: 300 readers who can help us by midnight tonight. I've been told that in the Mother Jones DC bureau last week, a debate raged over whether or not it's only crazy cat ladies who leave the air conditioner on all day for pets. I can see both sides: Sure, it's pitiful to see dogs pant and cats make themselves as flat as possible to beat the heat, especially during gnarly heat waves. And yes, it's true that pets are unable to doff their fur coats. On the other hand, their ancestors lived outside for eons before we domesticated them, so surely they must be heartier than we give them credit for. What's more, round-the-clock AC is exorbitantly expensive and contributes significantly to climate change, as the New York Times recently reported. Because of the soaring demand for air conditioning worldwide, and because the gases emitted by modern cooling equipment are extremely potent planet warmers, scientists estimate that AC units could account for a staggering 27 percent of global warming by 2050.

So is it really necessary to chill Fido all day long? I decided to call a few veterinarians to settle the argument once and for all. Dr. Helen Myers, veterinarian at the ASPCA's Animal Poison Control Center, had this to say in an email: When the temperature and humidity rise, it becomes crucial to keep our pets comfortable and safe. ac unit not coming on inside or outsideAnimals cool themselves by panting, a process of exchanging warm air from their lungs for the cooler air outside. what size central ac unitThis cannot happen when it is hot and humid, which leads to increased risk for heat stress and exhaustion. average cost for new ac unitLeaving the air circulating with fans or, better yet, leaving the air conditioning on will help to keep pets cool and healthy.

Thermostats should ideally be set at 78-80 degrees, an appropriate comfort level for most pets. Basements are typically cooler than the rest of the house, so if your basement is a comfortable place for your pet to be, having them spend time down there during a heat wave is also an option. Pets should also always have access to fresh water, as they can get dehydrated. Both cats and dogs are susceptible to excessive heat and humidity, but cats are more likely to control their activity so as not to add heat from muscle activity. Elderly, overweight, and pets with heart or lung diseases should be carefully watched, as they are highly susceptible to heat stroke. Pets with short muzzles like pugs, bulldogs and Persian cats are at a higher risk of becoming overheated because they cannot effectively pant. These pets should be kept in rooms with air conditioning so they can stay cool. Kimberly May, a veterinarian and spokeswoman for the American Veterinary Medicine Association, added that it's important to observe your pet and adjust the indoor temperature according to its particular needs.

"Keep an eye on your pet and see where your pet hangs out," says May. "If your dog is constantly by the AC vent, you probably shouldn't turn it off. But if you see the dog sitting in the sunlight, you might have a little more leeway." As a general rule of thumb, cats are often slightly more heat-tolerant than dogs, and for both species, the longer the fur, the more uncomfortable the animal will be in extreme heat. As for the argument that animals don't need AC since their forebears dealt with heat just fine, May doesn't buy it. "We've domesticated them and ruined all that," she says. "It's not smart to make an assumption about their needs based on their ancestors. We've changed their diets; we've changed a lot of things." A few other tips from May: You can try putting ice in your pet's water bowl, but only if your animal is comfortable with it; some cats and dogs are freaked by ice and won't drink ice water at all. Some dogs like the pricey cooling pads sold at pet stores and on the internet (this one is $79.99 on eBay) but others won't go near them.

Walk dogs in the early morning or evening, and keep the walks short. Don't go running with your dog, since dogs will keep going, even if they're overheating. How can you tell if your animals are hot? Why, compare them to pictures of sweltering critters on the internet, of course. A few to get you started: These cats are eagerly awaiting the unveiling of their cooling station: Dog in a cooler: Here's a hot cat hanging out by a window: Here's a hot cat in Tokyo: And here's one who finds a potted plant cooling:Dear Lifehacker,It just got sunny in Seattle and no one here has a real air conditioner. I need to find something to make it through the summer. Do I have any alternatives besides a small window unit? What's the most effective air conditioner I can use for an apartment? Dear Sweltering,From here in Atlanta, I feel your hot, sticky pain. The bad news is that if you're looking to keep a room cool, no matter what solution you go with, you'll need to pump hot air from the inside of your house to the outside.

This means you'll either be going through a window or a wall. Unlike heating a room, which can be done with a space heater that you just plug into an outlet, air conditioning requires a lot more parts and can get expensive. The good news, however, is you have plenty of options to choose from. All of the following possibilities can only cool one to two rooms at a time, max. They'll also need a way to pump hot air from the inside of a building to the outside. To get started, pick the highest priority rooms that have outside walls, then use a BTU calculator like this one to figure out how much cooling power you need for a given room size. Also, be sure to brush up on your A/C terminology before you go shopping. From there, it's time to decide which type of unit is best for your home. Before you rule out window units entirely, be sure you've exhausted all your options. While some A/C units are a couple feet wide and designed for roughly standard size windows, there are mini air conditioners that can get as small as 14" wide.

Many of these are designed for casement windows, which open horizontally instead of vertically like most slide windows. These devices are taller instead of wider. It may be difficult to find one that fits perfectly, but it's worth taking the extra time to look around before moving on to the more complex options. The advantage with window units is that all the important parts—the compressor, condenser, expansion valve/coil, etc.—are all in one big box. The installation of these is much simpler and they're very portable. Be sure to thoroughly search for a window unit before exploring other options. Find out what type of window you have and see if other people have a similar problem. If you absolutely can't find a window unit, it's time to move on to more elaborate solutions. Window units provide the most cost-effective and painless solution to cooling a single room. The units are relatively cheap and they have a lot of cooling power. If you're renting or want to avoid serious wall modification, this is the way to go.

The simplest non-window based option is a portable A/C unit. These are devices that usually sit on the floor near a window. Hoses will carry air inside and out through a window. Typically, these units will come with adjustable hose frames to place in the window that keep them in place. Technically, all the parts are physically in one box, but you'll still need a connection to the outside world for them to function. When deciding on a portable unit, you'll have to choose between single or dual hose systems. A single hose system uses just one tube to pump hot air out of the building. The trouble is that this reduces the air pressure inside your home. This causes more hot air from the outside to come in through cracks in doors and windows. The A/C unit has to work extra hard as a result, which is a terribly inefficient system. It's not a huge concern if you're trying to cool a small space, and these devices are generally less expensive. For a larger home, though, the extra energy costs can rack up fast.

Dual-hose units, on the other hand, cool the hot air that's already inside the house and returns it to the room from whence it came. To keep the unit itself from overheating, a second intake hose pumps in air from the outside to cool the device and then pushes it right back out again. This system is much more efficient because the device isn't constantly working against itself. Dual-hose systems are almost always the way to go unless you only need to cool a very, very small area. Just keep in mind that some units can get pricey.Whichever model you choose to go with, though, a portable hose unit should probably be your last resort. This is for those who absolutely can't use a window unit and aren't able to do any wall modifications. As Consumer Reports points out, they're costly and not very efficient in general. A similarly-sized window unit will cool better than its portable counterpart.This is where you start to get into some heavy lifting, but you also get a much nicer unit. Split units consist of two parts: the indoor component that you can mount on a wall, and the outdoor component that sits cozily next to your home.

The upside to this is that you can hang the device in a place that looks good instead of setting a giant box awkwardly near whatever window is available. The downside is you'll almost certainly have to start drilling holes. A "ductless" system might sound like a bit of a misnomer to the layman. All "ductless" means is that you don't need to have a complex system of action movie hero escape routes running throughout your entire home. You will, however, need hoses running from the inside of the room you want to cool to the outside condenser unit.The good news is that you may not need to do too much work on your walls. If you know how to run wires or hoses through walls, split units are comparatively simple to install on your own. As with any project where you have to drill holes in a wall, though, don't tackle a project like this unless you're sure you know what you're doing. A split system is a great option if you live in a hot region and need to cool a large area inside your home.

Their cooling power is among the closest you can get to real central air without tearing apart all your walls and ceilings to install. The two main disadvantages here is that these units will be among the more expensive you can find, and you can't move them from room to room like you can with a window or portable unit. You will also still need multiple units to cool separate rooms. By far, the most complicated option is a wall mounted air conditioner unit (otherwise known as where Dexter keeps his secret box). This type of device is very similar to the window system, except instead of using a pre-existing hole in your wall, you have to cut one instead. This involves watching out for pipes, wall studs, and generally ensuring the stability of your home while you make a hole big enough to fit a small person through in the side of your abode.Wall units are the kind of project where if you don't already know you can do it on your own, you should talk to a professional before getting started.

The upside to going this route is that you can find units that are much closer in price to the inexpensive window-based options. Of course, what you save in hardware costs you could end up spending on installation. Also, this may not be an option if you live in an apartment or dorm room. However, they have a lot more cooling power than portable A/C units, and are even more efficient than window units due to the much tighter seal. The energy savings can be well worth the trouble over the long term.We'd be remiss not to mention other alternatives to air conditioning. If you need something that works in a pinch, we've featured five effective DIY alternatives to air conditioning, and we've also asked you your favorites—and got a lot of great answers. Unfortunately, none of these options are going to be quite perfect for every home, but with some ingenuity, you should be able to keep yourself a bit cooler and more comfortable. No matter which option you pursue, you'll need to spend a decent chunk of change to get a proper air conditioning system set up.