Trying to understand our gas usage!

I got my gas bill today, and like others I'm shocked with how high it is. But for me it's more than just the price per kwh that's causing the problem it's the number of kwhs used as well. We've recently moved, and our usage in our new house is much higher than in the old, but I don't understand why.

In the old house we had a (approx) 7yo GFCH system, 1yo gas fire that was used almost every night in the winter, and a very old (harvest gold) gas cooker. Or max usage in the 2 years worth of bills i have is 100 hcf, but usually it went from 30 to 70. The heating was on an hour in the morning, maybe another 2 in the evening. House was about 900 sq ft terraced, and had double glazing but no insulation in the attic.

In the new house we have a (I'm guessing by the 088 number on the installation sticker) 10yo gas boiler, no electric cooker, and a gas fire that's never used (it's in the dining room). The heating is on an hour in the morning, an hour in the evening. Our bill was 125 hcf. As it is we're freezing here, but we refuse to turn up the heat until we get the double glazing installed (next month)! House is about 1200 sq ft terraced, insulated attic.

Does anyone have a logical explaination for why we'd be using so much more gas, when it seems like we should be using less?

Do you know what wall construction methods were used in the two houses? This will have an impact on heat retention. What is the orientation of the new house versus the old? North/south facing? Also, the older boiler may not be very efficient.

The old place was ex-council, 1960ish, made with shutters. Walls were made of everything and anything. South facing.

Current place is 1950s and we think concrete block, although we're not sure, as we haven't had to drill into anything yet. Definately going to find out when the windows get done. It's west facing.

I've sorta accepted it's got to be down to the boiler, but it still seems like a huge jump. Might have to get Bord Gais out to give it a service, and get some advice.