Great Ideas Charlotte! I commend your thinking of the use of geothermal loops (or really any heat recovery for low grade energy during cold winters) supplemented by water source heat pumps. In Toronto though, how could we claim net zero though if we cant really control emissions at the grid generation level? I checked today and 20% of electricity in Ontario is generated by natural gas (not zero carbon). So if we use the sewer/geothermal supplemented by heat pumps for heating, you are not emitting carbon on site but 20% of that electricity you use for heating has a carbon footprint. I understand that we can use solar/battery storage to make sure we generate/store renewable electricity to claim net zero, just wondering if you have the data/numbers to support?