Energy Efficiency Questions
My wife and I are in the process of designing our home in Houston, and it willbe about 4300 sq ( the mcmansion we did not want ). this forum has been great with details, but looking at the big picture on roi for energy efficiency and comfort. in my climate, does it make sense to go from our builder base selections to the following upgrades.
1. 14 seer ac to 16 seer or above ac
2. 80% energy efficiency furnace to 90% or above
3. the ducts are insulated at r-6, should insulate more
4. does it make sense to go from aluminum to vinyl windows, or should i just look at the u-factor and solar heat coefficient.
5. tankless water heater or higher efficiency traditional water heater or solar water heater.
6. we are considering icynene insulation. thoughts? what are the hvac considerations in a totally sealed home.
Before you commit to 4300 SF please look into the 'not so big house' series authored by Sarah Susanka. Chances are you don't need anywhere near that SF
That said, responding to your numbered questions:
1) In Houston definitely consider a two stage heat pump of SEER 16 or better.
2) Houston winters are mild; a heat pump meets both heating and cooling needs without the added cost and complexity of a gas furnace...at least get the upfront and predicted operating costs of the alternatives
3+6) Consider pulling the attic into the conditioned space via closed cell spray foam applied to the roof sheathing. Infiltration and duct losses drop way down. Closed cell (vs Icynene) adds both a vapor barrier and structural strength.
4)Select windows according to your aesthetic preferences. Look for long warranties. Tune windows according to exposures - west glass should have very low SHGC, north glass not so much.
5) Consider a heat pump water heater - they work well in southern climates, twice as efficient as conventional water heaters and provide useful cooling and dehumidification.
6. Consider a ventilating whole house dehumidifier for the minimal amount of fresh air ventilation to provide enogh fresh air to purge the indoor pollutants and renew oxygen when the home is occupied during calm weather. This will also keep the home <50%RH during damp weather and when the home is unoccupied with the a/c setup or off.
Originally Posted by watercop
Ultra-Aire/Honeywell/ Rheem etc. good brands.
Bear Rules: Keep our home <50% RH summer, controls mites/mold and very comfortable.
Provide 60-100 cfm of fresh air when occupied to purge indoor pollutants and keep window dry during cold weather. T-stat setup/setback +8 hrs. saves energy
Use +Merv 10 air filter. -Don't forget the "Golden Rule"