Older houses leaked and, to a degree, are uncomfortable and energy inefficient. We may think a cold room is standard in houses or a wood boiler needs to heat our house to 26C in the winter. We get use to opening windows in winter to get some fresh air in the house, or even cool down an overheated house.
This is number one, so I put it first. We live in our basements as much as we live on our main floors now. So the days of cold basements are done. You want comfortable temperatures everywhere in the house.
Whether you have radiant or forced air, you want to be comfortable. Zoning allows you to use one source of heating or cooling to meet the different temperature requirements throughout the house.
Everything should be efficient.
For radiant – the boiler, pumps, piping, and distribution needs to take care to ensure high efficiency. This means looking at variable speed pumps; adequate pipe sizing to reduce flow restrictions; efficient boilers; and a distribution system layout that allows you to heat with the minimum temperature water you can.
For air systems, you basically want the same – adequate sized ducting for air flows; proper returns; variable speed blowers; and staging equipment to match uneven cooling and heating loads.
This is not your heating and cooling system. Codes require a constant fresh air ventilation for buildings. There are workarounds that are poor choices, but are available to the budget conscious. Really you need to be looking at heat recovery ventilators or equivalent. Read the first sentence of this paragraph again.
Controls can help a system and they can get very complex very quickly. At their basic they just turn equipment on/off without us being around.
We can start adding basic features such as setbacks and weekly scheduling. We can also get more complex with remote controlling and monitoring; weather monitoring and predictive heating or cooling; and zone controls.
Ideally, controls should be like your system. You should not have to worry about it once it is set up.
Overall you want the ambient temperature of the house and all its areas to be comfortable for you to live in. Secondly, you want lower energy bills.
It does not matter whether it is geothermal, a propane boiler, or a gas furnace – all systems can get you there.