HOMEFRONT COMPASS / ONE HOUSE, ONE DAY
A shower fogs the mirror, breakfast fills the kitchen, and by afternoon one bedroom is warmer than the rest. Follow a fictional house through six hours of its day, and read what EPA, DOE and ENERGY STAR say about each one.
Start at 6 AMTHE SHORT ANSWER
Clearing out what daily life adds to it. Showers and cooking load the air with moisture and cooking emissions, and fans and hoods that vent outdoors carry them off. Windows let in daylight and some heat. Ducts and the shell of the house affect whether every room stays comfortable. And a house sealed tight to save energy still needs fresh air coming in.
The house in this story is made up, and its drawings are diagrams. Nothing here looks at, measures or judges your own home.
SIX HOURS
Pick an hour. The drawing lights up the room in use, and the note with it gives the official guidance for that moment.
Hour 1 of 6: 6 AM, the bathroom.
HOUR 01 / 06
6 AM · SHOWER
The day starts with a hot shower. The steam has to go somewhere, and in this house a ceiling fan is meant to carry it out.
WHAT EPA SAYS
EPA's remodeling guidance says a working bathroom fan is more than a motor making noise: it has to move enough air, and send it directly outdoors, not just into the attic or another space in the house.
Read EPA's pageThe drawing has no duct to follow; where a real fan's air ends up is something only the house itself can show.
THE WHOLE DAY
The same six hours on one page, each with the official source it rests on.
6 AM · Shower
The day starts with a hot shower. The steam has to go somewhere, and in this house a ceiling fan is meant to carry it out.
EPA's remodeling guidance says a working bathroom fan is more than a motor making noise: it has to move enough air, and send it directly outdoors, not just into the attic or another space in the house.
The drawing has no duct to follow; where a real fan's air ends up is something only the house itself can show.
Read EPA's page8 AM · Cooking
Eggs on the front burner and toast in the oven. Breakfast adds moisture, cooking smells and other emissions to the kitchen air.
EPA's cooking guidance says that if your range hood vents outdoors, turn it on whenever you cook, leave it running 10 to 20 minutes after you finish, and use the back burners when you can.
A hood over the stove says nothing about where its duct goes or how much it catches.
Read EPA's pageNoon · Light
Midday, and the living room is at its brightest. Daylight comes through the glass, and so does some of the sun's warmth.
DOE's federal guidance on buying windows notes that windows, doors and skylights use no energy themselves, but they do add to the heating and cooling loads of the buildings they're in.
How the sun moves across each side of a house What the numbers on a window label mean
Which way a real window faces, and what its glass is rated for, are questions for the two tools linked here.
Read DOE's page3 PM · Warm room
By three o'clock the back bedroom is warmer than the hallway, and the afternoon nap moves to the couch.
ENERGY STAR lists rooms that are too hot in summer or too cold in winter among the comfort problems that sealing and insulating ducts can help with.
Why is one room hotter than the rest of the house?
This story picks no cause for its warm bedroom, and it can't pick one for yours.
Read ENERGY STAR's page7 PM · Air
Everyone is home, dinner is on the stove, and the house is at its busiest of the day.
EPA calls cutting pollution at its source usually the most effective step, with more outdoor air as another, and says to weigh ventilating carefully when smoke or other outdoor pollution is nearby.
Nothing here measures the air in any room, indoors or out.
Read EPA's pageMidnight · Quiet
Lights out. The walls, attic, ducts and equipment keep working while everyone sleeps.
EPA says tightening a house is essential for energy efficiency but can let contaminants that a leakier house would dilute build up to unhealthy levels, and that weatherizing without proper ventilation can harm indoor air.
The drawing marks the attic, not real airflow; combustion, electrical and ventilation work needs a qualified person on site.
Read EPA's pageKEEP GOING
To evidence about the house itself. Airflow, heat and the way a real wall or attic is built have to be looked at in place, so start with what you can observe and with the agencies that set the guidance.
Updated · EPA, DOE and ENERGY STAR pages opened October 13, 2026HOMEFRONT COMPASS / KEEP EXPLORING