HVAC Concept Discussion

[n74tg]

I don't know if this is the right forum to begin this discussion in.  So, moderators, if you need to, feel free to move it to where you think it belongs.

Like many of you, I too am building my own place.  Glenn's "AC Spacepak" topic made my thinking take a detour down a different road for a while.  I am very worried about the future cost of energy, specifically natural gas for heating, and electricity for cooling (and heating). 

Right now, I am leaning toward central air and heat in the house being built, but I've begun wondering if we get some future significant cost increases in energy, that trying to heat and cool the whole house may become cost prohibitive.  If that happens, then a lot less costly alternative will be to NOT heat and cool the whole house.  In my mind, with a central hvac system closing vents won't make the system run any cheaper (that could possibly be a bad assumption).

So, maybe to begin this discussion I will ask a question or two.

Let's assume that we are in for significant and possibly prohibitive cost increases in the energy that we use to heat and cool our homes.  What do each of you think about merits and demerits of individual room heating and cooling; ie window units, and/or other individual room heating and cooling methods?

 

[glenn kangiser]

We already do that in our house in the Valley where temps go near 100 for much of the summer. 

[ScottA]

I think window units are more cost effective for cooling so long as you remember to turn off the ones not in use. Also window units will have a lower upfront cost. If you are in a humid climate removing moisture from the air maybe more important than cooling it. An A/C that's just barely big enough will be more effective at removing humidity. As for heat you should look at the best fuel source. For us it's wood which we can harvest for very little cost in $$$. Unless your place is pretty large having more than one wood stove doesn't make much sense. If wood isn't an option I'd look at some sort of radiant heating which you can zone off. Fuel would depend on your local. If oil runs low electricity may be a better option long term. Regardless a smaller well insulated home that is designed to use the sun to it's advantage will save the most money in the long run IMO.

[CREATIVE1]

One of my clients is involved with this company which provides solar air conditioning..   $$$$, but the website has lots of technical information.

www.solarsa.com

[MountainDon]

One of the problems I have with window A/C's is their noise level. The other is it seems more difficult to direct the air flow so it doesn't blow directly on me. Maybe I'm a nit picker.   

[John Raabe]

Make sure the design, insulation levels, passive ventilation, landscaping and lot placement are all working in your favor first. These are the free and near free energy choices that will work for the life of the house. Then, zoning the heating and cooling makes a lot of sense. As costs go too high you can retreat into a more core area of the house and let the other areas serve as buffers.

My long term guess is that electricity will be the lower cost fuel of the future. Using small heat pump units for zoned heating and AC should be a good choice in most mixed climates.

[MountainDon]

My long term guess is that electricity will be the lower cost fuel of the future.

I agree completely. All the more reason to invest in solar PV or maybe wind generation depending on where you are. I really think more people should consider a grid tie system, with net metering, over being totally off grid. My reasoning is that grid tie obviates the need for an expensive battery bank and their maintenance. Grid tie net metering has your meter running backwards when your system produces more than you are using at that time. Then you can draw from the grid when your demands exceed production. With proper system sizing you can average your use and generation out over a year to the point where you owe the power company for very few KwH worth of electricity.

Making electricity is easier than making fuels to burn.

[n74tg]

Don:
I don't think Arkansas does net metering yet.  If memory serves, you can give power to the grid, but you don't get any credit for it.  Of course that could change in the future.

[MountainDon]

Dang! That sucks. Net metering is about as good as it gets... you get 1:1 credits for your generation, BUT with most systems you can NOT make money at it. Our local power company is typical as far as I can tell when it comes to power companies that do 'net metering". They do not pay you at all. Period. That's why I say size the system correctly so you make just about what you use, averaged over a year. The credits from one month carry forward and are applied against future bills, even months down the road.

[Erin]

Neither Nebraska nor Kansas buy power back, either... 
(I'm not sure about credit, though)

So far as room A/C--  Of the dozen homes I've lived in since childhood, only one had central A/C.  Even my folks' three-story Craftsman in muggy eastern Nebraska, has had nothing but window A/Cs.  (though in their wealthy middle age, they have more of them!  lol)

Like Don, my only real complaint with window units is the noise. 
In our current house (where our utilities are free for as they're a job perk w/ the house), we have three, samll window units.  On truly hot days, we'll have all three running and a couple of fans, too, to circulate.  Part of that though is the fact that this house is a ranch-style and wasn't built for proper circulation. 

In the house we're building we're going to use either window A/Cs or a swamp cooler or two.  But even before that, we're doing as John suggests and building to gain the most from our environment (breeze, shading, insulation, etc)

[MountainDon]

Neither Nebraska nor Kansas buy power back, either... 
(I'm not sure about credit, though)

Something made me go and check out the local power company regarding their latest solar power info. Lo & Behold! They have made a change for the good!!   

There is a program, under which they WILL pay you for all the excess power generated!! And not at some lowball 'avoided' cost rate. Currently they will pay 0.13 per KwH. That's better than even the highest rate we'll be paying, even with the increase that's coming very soon. (Rates are tiered in three steps,  up to 200 KwH a month, 201-700, and 701+, escalating as your use bumps from one to the next.)

The only catches are, your equipment must meet their standards and you must pay a $100 application fee. Otherwise even if you overproduce you will not be paid. Still, a fair enough deal.

Part of the reason for this will be that it helps them meet their legally mandated alternative power generation quotas.

[n74tg]

Well, well, well.  After rereading the net metering posts (thanks Don and others) I did a little research tonite and in fact Entergy Arkansas DOES offer net metering.  So far they won't pay you cash if you overproduce, but they will carry your overproduction credits forward for future use. 
 
So, looks like I will be looking into solar pv more, AND after reading all the posts on users who do not have central ac, I may just go that way too.  Sure would make building this house easier.

[glenn kangiser]

If planning to us window units ahead of time you can make a dedicated opening in the wall for the unit rather than wasting  window space.  Foam crack filler bars can be used to seal it or as a filler for caulking.  A power plug can be placed inside or out as needed and units can be had that have heat also.  The one pictured is a heat pump unit -- don't waste your time and money on it.  Get the standard room A/C - heat unit.

[JRR]

Nice looking room!

I agree with the concept of a special/dedicated wall opening for a room ac unit.  "Everything else being equal"; a location near the floor, and near the center of the wall, might be better for noise concerns.  Furniture, tables, rugs, etc ... will all help to muffle the noise.

Of course, a "split unit" would even be better.  Does any USA retailer sell them?

[glenn kangiser]

Thanks, JRR.  That is at our conventional house in the valley - 75 miles away.  That was the remodel of the old house I did for Sassy.

My concern there was mostly the A/C and getting the cool air to mix with the warmer air, missing the furniture and having a straight shot toward the kitchen through the archway.

[n74tg]

Glenn:
Did you build the "conventional" house too?  About how big is it, number of rooms, and number of window units.

[glenn kangiser]

It was built in 1952 by a preacher - pretty fair construction - no insulation.  We had the early foam insulation foamed in in 1980 or so.

I remodeled it a bit at that time too and added on a 2 story addition in roughly the shape of a water tower which was a common structure in our area.  I added a extra bathroom and hallway between an existing bedroom and bathroom.  It is around 1700 sf total - about 25 x 50 plus the addition.

It has the kitchen/dining combo plus the living room, 4 bedrooms (1 used as an office) hall/bookshelf library, 2 walkin closets, bath and a half, utility room and enclosed porch, with a small foyer at the front door between the living room and dining room.  We have 2 player piano's there and a built in wall shelf.





We have one window unit in the master bedroom/bath/walkin closet section and the other shown in the living room/kitchen side of the house.  We also have a small wall mounted A/C in each of the addition rooms. The one remaining bed room is used for storage and is excessively hot in the summer.  The heat pump freezes up soon after it is started and does not heat in the winter.  The combo unit in the master bedroom is pretty good. 

The house is heated with a Toyo oil heater in the winter - about 120 gallons diesel per year.



http://www.toyotomiusa.com/products/laserventedheaters/L-60AT.mv

[FrankInWI]

just bought LP water heater, it was a clearance, and floor model, and I got 10% more off by taking out credit card. 
After I left with it, and sent it up to our dacha with my sons, I wondered why the heck I bought an LP one.  Seems like gas / electric prices diferential is changing, and it's easier to turn off and turn back on electric for the weeks we're not up there.
oh well.... now to decide on heater for the upper (have LP garage heater for lower).  Seen the Toyo you have glenn, and wonder about the practicality of getting fuel oil these days. 

[glenn kangiser]

We just use diesel but the cost is going up.  It's easy for Sassy to use though.  It's pretty high tech and about 98%? efficient recovering even most of the exhaust heat.

[mvk]

Glen
Nice looking place, not bad for a chainsaw and adz, but how did you get the Bobcat out
Mike

[glenn kangiser]

Sorry you had to see that, Mike.  It was before I realized I was an earthdweller.

Can't imagine living in a place like that anymore, but Sassy has to go there every other week to work.

[Dilly]

I am not certain how you buy diesel in the states but in Canada you can use farm diesel which is a lot less.My farm buds have been using farm diesel in their trucks for years.  Just don't get caught but for home use maybe you can by a tank or put a pumper at one of your farm friends and go over and fill your Jerry cans once every week or so.  Just a thought.

[glenn kangiser]

I have equipment so have a red diesel card.  About a buck cheaper here I think- regular diesel was $5.19 today.

[Dilly]

Your price of diesel and ours is getting closer. We are running at 1.27 a liter which is about 5.65 an imperial gallon which equates to about the same. Our regular gas is just about the same price. I have an suv so it gets scary.  I am not travelling far these days. Travelling in Ontario which is a long drive anywhere is down about 30% after our holiday weekend.

[peternap]

I have central heat/AC in my burb house.  I haven't used the AC in 10 years. It's a lot chwaper to use window units. The noise doesn't bother me (too many years shooting without hearing protection )

Glenn, I looked at your remodel......I hate you!