Last winter, significant snowfall and dangerous cold tested the power grid across the state of Texas. The snow and extreme cold caused ERCOT to declare the highest level of energy emergency in the state of Texas. Oncor and other Texas utility providers rotated electric outages to protect the electric grid. These typically lasted 15 to 45 minutes, but could vary depending on winter weather and conditions.

So, with winter on its way once again, what can you do if the power goes out for several hours? Here’s how to stay safe in these dangerous conditions:

DO: Conserve body heat

When the power goes out, the most reliable source of heat may be your own body. Prevent heat from escaping by putting on extra layers, blankets or accessories like hats and gloves. If the cold is severe, your bed may be the warmest place. Use extra blankets and coverings to trap body heat; this is an especially good way to keep children warm.

Emergency blankets made of heat-reflective, thin plastic sheeting may also come in handy if quilts aren’t cutting it. Sleeping bags are also a great alternative, as they’re designed to withstand cold temperatures and zip all the way around your body. However, beware of overdoing it.

Layers of loose-fitting, lightweight, warm clothing will keep you warmer than a bulky sweater. If you feel too warm, remove layers to avoid sweating; if you feel chilled, add layers.

Hypothermia and frostbite are two conditions that can occur when you’re exposed to extremely cold weather for too long. People with inadequate clothing, heating or blood circulation are most at risk.

DON’T: Run your car or burn charcoal inside

Car exhaust creates heat that can quickly warm up a room, but it also creates carbon monoxide, an odorless, colorless gas that can cause sudden illness and death in confined spaces.

Carbon monoxide can build up quickly indoors and can linger for hours and at elevated levels can cause significant harm and even death. Make sure that your home is equipped with CO alarms, and that they are properly calibrated when installed and have a digital display and battery backup function.

In a power outage, that battery backup function is essential. But if your alarm isn’t working, know the signs of carbon monoxide poisoning: headache, dizziness, weakness and confusion, among other symptoms. If you suspect there’s been a carbon monoxide leak in your home, get fresh air immediately and call 911 if you need medical attention.

DO: Create smaller spaces within your home

Layers, blankets and sleeping bags only do so much to conserve your body heat. Small adjustments to your home can also help keep you warm. Close off unused rooms, and stuff towels or rags in cracks under the doors. Cover the windows at night.

If you have the space, keep all your family activities confined to one space and close any interior doors to trap the heat inside. Keep your curtains closed, unless you have a window that brings in sunlight.

In general, the smaller the space, the warmer you’ll be. That means erecting a tent indoors, as one Facebook user suggested, isn’t a bad idea to combat extreme cold — especially if multiple people fit inside.

It may seem obvious but avoid going outdoors. If you do need to leave your home, avoid exposing the interior to cold air.

DON’T: Keep gas stoves or ovens running

It may be tempting to use your gas-powered kitchen appliances to produce heat during a winter storm, but that could cause more harm than good.

During a power outage, do not try to heat your home by using combustion appliances including gas stoves or ovens, outdoor grills or clothes dryers. Never operate any gas-burning heater or other appliance in a poorly vented or closed room, or where you are sleeping.

That’s because combustion appliances produce toxic fumes such as carbon monoxide. Since they’re not designed as space heaters, gas ovens and stoves may go out or burn inefficiently, which could lead to carbon monoxide poisoning. Appliances could also pose a fire hazard, especially if they’re left on for long periods of time.