Answer:
D. Opening the front door in winter to filter and clean warm ai
Explanation:
All of the following are examples of ways to improve energy efficiency of heating systems, except _______.
A. Closing off rooms that aren’t in use.
B. Frequently cleaning the furnace filter.
C. Fixing cracks in the walls and floor.
D. Opening the front door in winter to filter and clean warm air
for an heating systems it is better to keep the front door shut so that all the heat energy does not escape outside.
when heat energy is within a closed system ,it can still be utilized to keep the inhabitants warm otherwise there will be an exchange with the cold from winter fall outside the air, and the heating system's efficiency will be reduced
 
        
             
        
        
        
Good are free zones bad is car pollution ext.
        
                    
             
        
        
        
No worry’s I am here to help
        
             
        
        
        
Use the right equation. To calculate the normal force of an object at an angle, you need to use the formula: N = m * g * cos (x) For this equation, N refers to the normal force, m refers to the object's mass, g refers to the acceleration of gravity, and x refers to the angle of incline.