Massive is probably not the right term. Yes, there is investment required in equipment and insulations, but a typical home will generate probably 10 tonnes of CO2 emissions, if it's burning fossil fuel, per year. Over 30 years that's 300 tonnes. A conversion, even taking into account the greenhouse gases involved with the equipment, is not close to that range at all.
On November 30th, 2020. See this statement in context.