contempary technology

By using microprocessors and equals manufacturers are now able to supply higher performing high-tech systems. 

High efficiency boilers (condensation heaters for example) are these days often far more efficient than their predecessors. Heating pumps reach a COP of less than 4. Officially approved but because of the fact that the needed Electricity has a COP of 0.5, is the energy gain altogether only half as long as we can’t gain electricity in a self-supporting way.
Pellet heaters are  environmentally very friendly 
but ask plenty of room for the container and that needs to be calculated also in the price of new buildings (this is also in force about or waterfree compost lavatories).
In a mechanical ventilation ( ventilation system D and E)  the heat of the extracted air can be passed to the incoming air. This is of course only profitable on good isolated residences and even obligated on passive residences. In order to keep the air healthy ,  a cleaning contract of the ventilation ducts is  recommendable.. Beyond that there is also the influence of air through positive ionization, whereto insuffient research has been conducted. Because of that, ventilation system C+ offers more benefits for healthy air (except in zones with polluted air), but  technicaly this is less efficient. System E (decentralized mechanical ventilation) hasn't these disadvantages, but it's still expensive.
The raising energy costs causes that even heat recovery from shower water, financially can be  intresting.

Installations using photocoltaic cells, have become depreciable. Keep paying attention to keep distance between your be and the  transforme. Grants in Belgium are the cause of that bad isolated residences now do have solar panels on their non-isolated roofs. The government urgently needs to change this!

Let’s search to low-tech solutions except for this (Unesco collects Traditional Knowledge) and no-tech like passive sun utilization, compact building, well isolating and other architectural interventions;
The future lies in using both hi- and lowtech. 

( diagram of Oertli)