Earlier quoted context omitted.
How efficient is Boinc as a heating application? It's an important part of calcuating its climate impact. Also, why old desktops only? Won't a brand new desktop running at 100% generate plenty of heat? Isn't the difference merely calculations per W?
Electronics do not move the needle at all when it comes to climate impact (in terms of heat dissipation). It's where the electricity is sourced that's the problem.
Given the electricity used, how efficient are (Boinc + my desktop) at generating heat? For example, is it equally efficient to use Boinc + Desktop to warm my office as it is to use a space heater, or electrical radiated heat?