Using 5,8KW less for heating during a cold January day

Progress:
Unfortunately, the progress from Thursday did not continue on Friday (nobody showed up to finish the work).

The last few days have been very cold, and as a result the aggregate stopped again today. Included below are the temperature statistics from these last cold days (with temperatures below -20C) and when the aggregate ran as it is supposed to:    

The last columns represent the results:

• Input air: this is the temperature of the fresh air that the ventilation systems sends out in the living room (after the heat exchanger and after the heated air from the heatpump has been added)
• Exhaust air: this is the temperature of the "used" air that leaves the house. When we lived in a "nei hus" ("no house") the temperature of the air leaving the house was 20C, but with the heat exchanger - the results show that we have managed to lower the temperature by as much as 26.9C (to -6.9C)
• Delta: shows a calculated difference between the outside temperature and the exhaust air (the lower values are the best - because we manage to transfer most of the energy from the exhaust air to the incomming fresh air)

I also wanted to estimate the savings of the new ventilation system compared with traditional air hatches. The assumptions and calculations are included below:

•  Previously, the recirculation of air was done through traditional air hatches
• The temperature of the "used air" that left the house through these air hatches was approximately 21C 
• We estimate that we have approximately 650 cubic meters of air in the house
• The ventilation system changes 350 cubic meters of air per hour at normal effect, and at maximum effect it can change 500 cubic meters of air  
• The volumetric heat capacity (VHC) for air: 0.001297 J/(cm3*K) and this translates to 126W/K for 350 cubic meters per hour  
• On the coldest day the temperature difference between "normal" exit temperature (+21C) and the JAHUS exit temperature (-13C) was 34K
• The calculated energy savings of the ventilation system was 4.3KW (at 350 cubic meters per hour)     
• Add to the 4.3KW the savings of the heatpump: at these low temperatures the heatpump effect is lower and the 1.5KW "put into" the heatpump we get approximately 3KW of heated air - a saving of "only" 1.5KW => a total saving of 5.8KW for heatpump and ventilation
• On top of the 5.8KW savings we can add the reduction in heating requirement caused by improved isolation (changed windows and doors, and added an extra layer if isolation in the cold attic): it is hard to measure the effect of the isolation efforts, but a low estimate is 1KW

The savings of 5.8KW during the cold days of January gives the following economic savings:

• Average price of electricity over a full year is 0.155 USD/KWh (0.85NOK/KWh - total delivered to a home in our area), but for January isolated the price is higher: 0.25 USD/KWh (1.4 NOK/KWh) 
• Hours in January = 744
• Estimated savings in January: 744hours* 5.8KW*0.2USD/KWh= 863 USD (4919 NOK)