Actually you will lose by increasing the size of the pipe coming out of the heater and going to the rest of the house. The hot water in the pipes will cool when water is not flowing through them. Before you get hot water to the fixture, all of that cooled water will have to be purged (wasted) before you will have hot water. What many of us do is to use a recirculating system which will provide virtually instant hot water at any fixture. Also, 1" is far too large for a house distribution system. Depending on the number of fixtures involved, 3/4" might even be larger than necessary. There are tables that will provide optimum pipe sizes. You should investigate a recirculating system before completing construction as the better ones require a return line...that's what makes the recirculation possible. There are several very good brands available and the cost is not too bad. Many have timers on the pump so they only recirculate at the set times. I have one that does not use a timer that has been in service 24/7 for several years without a problem. If/when the pump fails, it is located where it can be easily replaced. Keep a watch on this thread, someone will likely provide the sizing information in better detail.