how much heat required to heat a room
2. Determine the total wattage needed for the room. Older homes with less insulation will use about 10 watts to heat each square foot. Newer homes with greater insulation values will only use about 6 watts per square feet. It will take approximately 600 watts to heat a 100 square foot room in a newer home.Older homes will need as much as 1,000 watts for the same room.. Calculate how large the baseboard heater will be. Baseboard heaters use about 250 watts of power for every foot of length. In a 100-square foot room that is part of an older home, the baseboard heater will be approximately 5 feet long. In a newer home, it will be about 3 feet long.