New HVAC system?

A few reasons have me considering an upgrade to my HVAC system.

1) My latest BGE bill. I used a whopping 1578 KWh of electricity in June - almost 3 times as much as I used last year. My A/C unit is running almost constantly, even after I had a guy come out and look at it. This doesn't seem normal. I have some holes in the house due to renovation (like ones into the attic), but I was surprised to see costs up this high. Maybe the 50" plasma and XBox 360 are to blame too?

2) Natural gas prices are up over 200% since January! (See the table of my energy costs below) Since this is the cooling season most people don't notice, but come winter this will lead to some hefty bills.

I know something is wrong with my gas meter so I don't think it's recording my full usage. I don't have a problem with this, but BGE has volunteered to come out and fix this issue for me free of charge. I haven't been expeditious in getting back to them. I don't know how this would increase my cost/therm, but maybe this is the case? I doubt it though.

3) My current A/C and furnace are at least 15-20 years old. I have a home warranty on my house, which has been used numerous times to repair my constantly ailing HVAC system. Each time the warranty company comes out they fix piece parts but it doesn't look like they'll buy me a whole new system. *sigh*

Baltimore Rowhouse Consumption Table*


Energy prices are also motivation to seal up the cracks in the ceiling and to actually insulate the attic. Yes, I have no insulation up there as I've been waiting to redo the upstairs bathroom before blowing it in. I'm a bad person with a carbon footprint the size China.

My buddy Dru works for a big HVAC company, so he's running some numbers for me. My prelim estimates have me thinking I'll need about need about 2 tons of chilling capacity. Pricing out some mail order split systems (both interior and exterior parts) gives me a range of about $1500-2500, plus installation. The $1500 system is SEER 13, while SEER 16 would run about $2500. I'm not sure the extra $1000 up front is worth saving me around $120 a year. I'd like to be green, but I also don't like to throw a bunch of money away. Also throw on maybe $1000 for install (I have no clue) and this is looking to be a pricey endeavor.

After the sizing is run I'll take another look at what the prices are and decide if I really want to do this. While it wasn't in the plan to upgrade this, the costs are making more and more sense.

*Some notes on my calculations. The prices I used are prices for electricity with all taxes and fees added on, and the gas costs are the commodity prices plus the delivery charges. Comparing bills I've noticed some interesting things happening with prices.

a) Surprisingly, the cost/KWh of electricity has stayed roughly the same. I had thought there would be a massive increase due to high commodities (coal). I wonder why prices have held steady. Any ideas?

b) While I see the commodity cost of natural gas has gone up 40-50% percent, what I don't understand is why BGE is charging 40% more for the delivery charge. Not sure why this would correlate with commodity prices.