This means that a poorly
insulated building with an inefficient heating system can achieve an excellent BER, provided that the high energy demand is offset by a sufficiently large solar PV array, for instance — even if that PV array was discharging all of its power into the grid or — in apartments, the landlord areas — and providing no appreciable benefit to the
occupant.
But if you do it on the cheap,
insulate improperly, throw in crappy windows and don't compensate for the leakiness of the existing
building by bringing in adequate fresh air, you can destroy a
building in ten years and affect the health of the
occupants.