By keeping your house at 25 degrees, you're setting the baseline temperature of the house (i.e. it will never be colder than 25 degrees, period).
If you can get some airflow, why not just set your house to like 19 degrees, and use the fans of your unit to equalize the temperature in your unit (19 degrees is the new baseline, it will probably keep the unit a degree or two hotter just by the ambient heat generated by your server).
For what it's worth a server is fine to run in this type of environment. What are the internal temperatures of your system? Is it overheating?
By keeping your house at 25 degrees, you're setting the baseline temperature of the house (i.e. it will never be colder than 25 degrees, period).
If you can get some airflow, why not just set your house to like 19 degrees, and use the fans of your unit to equalize the temperature in your unit (19 degrees is the new baseline, it will probably keep the unit a degree or two hotter just by the ambient heat generated by your server).
For what it's worth a server is fine to run in this type of environment. What are the internal temperatures of your system? Is it overheating?