Home improvement question -- which should I do?

Factual Questions
1

I’ve got a house built in the late 1950’s that, to be kind, is far from energy efficient. We recently replaced our water heater with a tankless model, but there’s a lot left to do. We’re trying to figure out which of the following three improvements would be the best to do.

First, specifics. We’re in Hollywood, and our two-floor house has an entire wall of windows on both floors. They are old windows, not insulated, not double-paned.

We’ve got a flat roof, I believe it’s called tar & gravel. To my knowledge there’s no insulation between our ceiling and the roof. (Our ceiling is tongue-and-groove wood slats, and I’m assuming there’s some plywood above that and then the roof tar. But I am not 100% sure of that, it’s just an assumption.)

Lastly, our air conditioner is old. About 12 yrs old, it’s a 3-ton model and we need a 5-ton unit.

In the summer, our top floor gets VERY hot in the late afternoon, the a/c simply can not keep up. So to deal with that best, which of these 3 is the best approach, assuming we can afford only one of the solutions.

1 - replace the a/c unit with a larger, quieter, and more efficient (SEER 16) model.

or

2 - replace the roof, and have insulation put down under the new roof.

or

3 - replace our windows with double pane, energy efficient ones.
(this is probably out of our price range… as an alternative, what about putting tinting on the windows to keep the sun out a bit?)

Anyone have suggestions as to which of those options would result in the most efficient energy savings and a more comfortable house?

2

4 - Plant a couple of trees and enjoy the shade?

3

Why do you believe you need 5 tons?

How many square feet in the house?

4

You’ve got a chicken and egg thing going here, don’t you? You can install the AC upgrade for comfort, but will be losing efficiency through the roof and windows. You can upgrade the roof and windows, thereby increasing the efficiency of your existing AC, but won’t be able to afford the new AC. Catch-22 and I’m no help.

5

Can’t do trees – we’re in a high fire hazard zone and are adamant about maintaining proper clearance from the house. So no trees allowed anywhere near the structure.

Currently 1,800 sq feet. So we really only need a 4 ton unit we’ve been told. But we’d like to add a 3rd floor (underneath…hillside house) eventually and figure we should have a unit that can handle the 3rd floor as well. Plus, wouldn’t a larger unit be able to cool a smaller house more efficiently?

6

With respect to the roof, are your ceiling joists visible? If they are not, then you can get insulation between the T&G boards and the roof, without tearing the roof off. If the joists are visible, you can put a new ceiling up underneath them and insulate the space. It may change the look of the room, but it won’t be all that expensive.

You can also look at putting drapes over your windows, that will cut down on a lot of heat from the sun. Awnings are a nice option there too, if it fits the house style.

I wouldn’t go tearing off the roof or replacing all the windows until trying the simpler insulation options and a new high efficiency A/C unit.

7

I think you need to get estimates for each of these projects. That will help in determining the payback.

At 1800 sq ft, you would typically need 2.5 to 3 tons—not 4 or 5. As to A/C sizing, there are many factors that determine the correct size; shading/trees, roof color, quality of windows, exposure orientations, R value in walls & ceilings, amount above/below grade, surface area of walls/windows, and the list goes on.

If the A/C unit has been taken care of at all—and if it’s a decent brand----you should get 15-18 years out of it. (and often 20) I would not be looking to replace it if you have other fish to fry.

In addition, a new roof or windows will reduce the need for A/C. Improve the envelope and you can use a smaller A/C system.

My 200 pesos:

  1. Get written estimates

  2. As to A/C, have a reputable HVAC firm do a “Manual J ACCA Load Calculation” done. Many will tell you they know from experience etc. No bueno. Have the Load Calc done. Make it a requirement of them providing the quote.
    As to A/C, a larger unit will not (read:not) be more efficient. An oversized unit will leave unnaccaptable humidity in the home and short cycle. Don’t fall into the “bigger is better” trap. It is not.

If you get better insulation and windows and revisit the A/C later (with a comprehensive load calc reflecting the improvements you’ve made) you’ll get a better system that is tailored to your new home.

8

Already have awnings. Well, the roof juts out over the deck and limits the sun a bit. Doesn’t matter, still gets very hot in there. And changing the roof inside sounds interesting, but I’d like to avoid it. Our ceilings are beautiful, and to be honest not sure how much it’d save. The roof is small enough and flat enough that we can replace it (and add insulation) for about $10K… I have a feeling redoing our interior ceilings wouldn’t be much cheaper. Maybe $1 or $2K at best.

And with our curtains drawn it still gets uncomfortably warm in there. There’s just no way to cool the house down enough or to keep the cool air inside.

We’re looking at staying in this house for a long time, so investing in the property is something I’m ok with, I just can’t do it all at once.

9

Raindog, thanks for the excellent info, good to know! I definitely always get written estimates, but didn’t know about… well, anything else you mentioned. =) Much appreciated.

10

I disagree with this in part.

If the A/C system is working now----and can be serviced----it is best to do the HVAC last.

New windows,roof etc make the envelope tighter and more energy efficient and reduce the need for A/C. (read: a smaller system that uses less energy) 12 years is not ancient—and if this system is working well I would do the other things first and plan for an HVAC upgrade once the unit is 15-18 years old.

11

No! It’s got to be sized properly. Going larger than is needed is inefficient. You’ll get more swings, it’ll run shorter cycles more often, and won’t dehumidify very well.

If you know that you’re going to eventually need a larger AC system due to expansion, then do what you can now with what you have. Either the roof or the windows. Any reputable HVAC engineer will calculate your heating and cooling requirements based on a lot of variables, of which your square footage is only a single one.

12

I’m not sure more roof insulation or insulated windows are going to do the trick.
You are not trying to keep the cold in but are rather trying to keep the heat out.
That’s what A/C does, literally pumps the heat out of your house.
Problem is your windows, even if they were triple pane, are still letting in sunlight that’s directly warming your house from the inside.
The more you insulate the more you’re trapping the heat inside making the AC do all the work.
If you can’t plant trees to shade those widows, or add exterior louvers, you’d probably be best off getting some reflective window tint installed.
Also you may want to consider exhaust fans for your roof to pump out some of the heat trapped inside.

13

Improve insulation, keep HVAC and run the fan (set fan to “ON”, not "AUTO) on the HVAC non-stop to keep the air circulated and balanced.

Nothing you do will ever keep hot air from rising and cold air from falling, so running the fan non-stop is one of the most powerful changes you can make. When it’s hot, slide that fan switch to “ON”, not ‘Auto’, and you will see alot of improvement.

14

You know, we used to do that and I had an a/c tech say not to, that it never gave the unit a rest and it would wear it down. Was he full of crap?

15

First, I would contact your electric utility (and gas if you have it) to see if they give free energy audits. If so, they’ll send an expert out to your house who will look at the details of your house and make recommendations, probably including payback times for each option. Did I mention it’s FREE expert advice, from someone who’s actually seen the details of your house (as opposed to a bunch of yahoos in the interspace somewhere)? Run, don’t walk, to the phone.

In the meantime, I assume you’ve already had the roof checked by someone competent to see when it’s going to need to be replaced?
Because if you need to replace the roof anyway, then insulating at the same time is a no-brainer and you can stop worrying about which option to go with and concentrate on saving up the cash for the new roof.

16

All you’re running with the fan switch set to ON is the fan motor. And it should be able to handle 100% duty cycle. I have a heat pump in a 3800SF house and the fan runs 100% of the time. When heat or cooling is called for, the fan speeds up or down as required.

As mentioned above it will help even out the temperatures in the home.

To open another can of worms, perhaps you could add an independant split system to heat and cool the top floor. These units are often wall mounted and the other side of the unit sits on the ground outside. Only a control/power cable and two refridgerant lines connect the two. A fellow I work with installed one of these in an added room and it works great.

17

That’s not cool air inside, it’s hot air.
You mentioned that it’s the upstairs that gets especially hot; that’s because the hot air rises up to there.

Look into installing an exhaust system at the highest point convenient, to blow some of that hot air out of the house. You can get systems now that are temperature controlled – they only exhaust the inside air when it is warmer than the outside air, or when it reaches a specific temp that you set.

By pushing this warm inside air out, you will give your existing AC a chance to keep up. It might be enough. And it’s a fairly cheap thing to do.

18

Your roof - visible tongue-and-groove boards on massive beams? Acres of glass? I’m guessing your house is an Eichler or some variant of that style. They’re nice to look at, but challenging to live in at times.

There is absolutely nothing between those boards and the tar and gravel. Those boards are 2" thick, and they are the roof “decking” so the only way to insulate is to do a drop ceiling.

If the roof is not in bad shape, you could coat it with “Snow Roof” - this is blindingly white stuff normally used to seal RV and “mobile” home roofs. You’ll get a few more years out of the roof and the bright white will reflect a lot of heat, effectively killing the huge passive solar gain that’s cooking you right now. This is easy enough to do yourself as long as you’re not afraid of climbing up on a roof and swabbing stuff the consistency of Marshamallow Fluff around. Cleanup is best described as “don’t make a mess in the first place and plan to throw away all tools used, as well as your shoes and pants.” Another option is to buy a few 5-gallon buckets of exterior white paint and swab that onto the roof. It’ll be less expensive than the Snow-Roof, but it also won’t last as long. The underlying tar will aoso probably bleed up through the paint in short order. But it will reflect some sunlight and heat.

Window tint is a very viable option. I’ll caution you that it’s technically possible to do it yourself, but for anything larger than about two by three foot windows, you will need at least three people to assist in spraying the glass, peeling the protective liner off the film, spraying the film and getting the slimy wet film onto the glass smoothly without creasing, tearing or touching the film to itself. The stuff is very fragile - if it touches itself, it’s toast. You may want to enquire at glass shops about having it done professionally. I did three mid-sized windows in my home, and it was challenging and I’m not particularly proud of the finished job - there are a couple spots where the stuff got creased and a couple spots where the film touched itself, resulting in clear spots and some new profanity in my vocabulary. On the plus side, it did make a big difference in how warm the room gets.

19

This is what I was going to recommend, too. There are several other benefits, as well, including being eligible for a tax credit if installed before year-end (IRS cite). The company in that link is even right here in Hollywood. They did the windows on my boss’s house, and he was very happy with their work.

We have no air conditioning at all, and our house gets unbearably hot in the Summer, so I’m planning on having a solar attic fan installed. My general contractor confirms that this will help a lot.

20

I’d never heard of an Eichler house, but yes, it’s very similar to what we have.

Friends of our neighbors have a similar house and put insulation on under a new roof, and apparently it made a huge difference. This thread is the first I’ve heard about it potentially trapping hot air in the house instead of letting it out, though, and it has me a bit nervous.

The vent sounds like an interesting idea, and Shayna, I just made an appt for an estimate from the window coating people you linked to, thanks. Also left a msg for DWP to see if they offer energy audits… I heard the used to but don’t anymore, but I want to find out for sure from them.

Great responses, everyone, thanks for the valuable info!