My suburban place came with a wood pellet burning fireplace for (mostly) a single room. My partner staying warm by running that costs about half the price of na

My suburban place came with a wood pellet burning fireplace for (mostly) a single room. My partner staying warm by running that costs about half the price of natural gas heating the whole place. Would be interested in ways to calculate emissions based on how many lbs/kgs of wood pellets vs. therms of nat. gas.