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Table 1: U-values for a typical three bedroom apartment
Typical 3-bed flat, mid terrace, mid-floor		U-value (W/m²K)
Total floor area	70 m²
Window area(aluminum frame, double glazed, low e)	7 m²	2·6
External walls	28 m²	0·35
Room height	: 2·3 m
41% of flat is living area (combined kitchen/dining/living area)

Table 2: Comaprison of glazing to floor ratio and window u-values
U-value (W/m²K)	% glazing to floor area
2·2 (elemental minimum U-value)	16·5
2·4 (double glazing, low e, argon filled)	15·1
2·6 (double glazing, low e)	13·8
3·3 (double glazing, argon filled)	10·7
3·4 (double glazing)	10·4
1·8 (triple glazing, low e, argon filled)	20·6
Assumes wall U-value of 0·35 W/m²K and electric heating.

Table 3: Comparison of the emissions of electric heating to gas based systems
	Option 1	Option 2	Option 3
	Gas-fired condensing combi boiler	Electric storage heaters, electric water heaters 140 litre storage, 2002 CO₂ emissions	Community heating – gas-fired boiler
SAP	120	98	120
Running cost (£)	93.72	135.94	93.31
Carbon index	9·6	7·4	9·1
CO₂ kg/year	869	1565	1033