Grow Lights Question

I am not new to gardening, but I am new to seed starting. I have two south facing bay windows that I am thinking of putting shelving units in for my seed starting. Will I still need grow lights? If I have to have lights anyway, I am thinking about not putting them in the windows. If you use grow lights and your house is room temperature, do you still need bottom heat?

If you're starting seeds you would probably still benefit from having lights, seedlings like to have many, many hours of light during the day, and especially in the wintertime even a south facing window won't have as many hours as they like (I leave my lights on from 6 AM until about 9 PM every day). I also still use bottom heat, the lights don't put out that much heat and I grow seeds that do better with bottom heat. Not all seeds need bottom heat, so it depends on what you're growing whether you'd need that or not (many seed packets will have info on ideal temp for germination which should help you figure out the heat mat or not questions).

A lot of my seeds have come from trades and have no instructions. Plant files does not include temps either... I guess I can google each seed name...

You could post the names of the seeds here too, or on an appropriate forum (annuals, perennials, tropicals, or a plant-specific forum like brugmansias, etc). Unless it's something really rare or unusual I'm sure you'll find someone who's started it from seed before. Or you could ask the person who sent it to you in the trade if they know--most likely they've started them from seed themselves.