Knauf Insulation » Solutions » 1.0 Introduction » 1.1 Buildings and Energy » Complimentary Energy Efficienc

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Energy efficiency and renewable energy are complementary. Insulation in a building reduces the energy demand. This means that in the drive for zero carbon buildings, renewable energy can be ‘downsized’ to increase resource efficiency and reduce fuel demand. Therefore, micro-generation with photovoltaic cells, wind turbines and Combined Heat and Power (CHP) become more viable options – making a highly insulated building structure essential.

Loft insulation

Loft insulation in an empty roof space, in the home or in the workplace, can pay for itself over approximately two years.

Solar hot water panels

Can supply over 50% of a building’s hot water.

Low energy light bulbs

Each bulb can save up to £9 a year in electricity costs.


Wind turbines Generate clean, pollution free electricity.	Cavity wall insulation Massively decreases heat loss through walls and is easy to install in older homes.	High efficiency boilers A condensing boiler can be up to 92% efficient.

Complex challenges exist for designers on both how to integrate renewable energy into building design and which type of renewable energy is appropriate for a project. Some types of renewable energy are more suitable for specific locations. The flow charts on pages 20-23 provide a quick reference guide for designers outlining the decision process for renewable energy options.

Insulating a home

The media has bombarded us recently with many ecologically friendly means of reducing our household carbon emissions. These range from photovoltaic cells on the roof, to lagging jackets for boilers. Table 1 ranks these according to cost, payback period and kilograms of carbon emissions saved.

Table 1: Costs, savings and paybacks

Method	Cost	Years to recoup cost	kg of carbon saved each year
Hot water tank insulation	£12	0.5	160
Loft insulation (150-200mm)	£250	2	1000
Cavity wall insulation	£500	5	750
Improved heating controls	£200	3	530
Draught proofing windows	£90	5	155
Micro CHP (combined heat and power)	-	-	200
External wall insulation	£1,900	6	2600
Internal wall insulation	£42/m²	n/a	2400
A-rated boiler	£1,500	13.6	875
Ground source heat pump	£7,300	18.3	2000
Photovoltaic electricity cells on roof	£5,000	33.3	1100
Solar water	£3,200	80	350
Windows single to double glazed	-	-	740