The HOUZE company's website is http://thezeroenergyhome.com/ , but is it a Net-Zero energy home? The website only claims to provide a 10 year zero energy payment warranty. No claims about about having its energy usage offset by renewable energy generation. They also mention that this provides "Energy Independence", but I don't see how substituting grid electricity dependance with natural gas supply dependance can really be called independence.
To me, the usage of the phrase "zero energy", is a sneaky bit of marketing used to confuse buyers into thinking this may be the equivalent of a net-zero energy home when in fact it is not.
Some may argue that by utilizing the waste heat of the generator, the utilization of the fossil fuel energy is therefore higher. This would be true only if existing power plants didn't already supply their waste heat to other industries or try to use it to generate even more electricity through technologies like thermocells. Additionally, to achieve higher energy utilization, the waste heat generated by the home generator would need to be consumed year round, even in the summer when domestic hot water and home heating needs are probably not enough to consume the majority of the waste heat.
If that wasn't enough, states like California use natural gas as the primary fossil fuel for electrical generation. However, their energy mix also includes nuclear and a growing share of renewable sources which have a zero-carbon footprint. Generating your own electricity from NatGas to lower carbon emissions would be disastrous in those states.