I don’t like using the heater or the AC so I’ve been insulating the townhouse.  My last project was replacing my 2 patio doors with vinyl low-E 4 patio doors.  That did reduce the temperature spikes but it still got warmer and colder than I prefer.  My latest project has been to put one inch thick foam insulation where the heat and cold are still coming through.  I bought a 8ft x 4ft sheet from Home Depot and cut it to size with an exacto knife.  The reflective side is supposed to face the sun.