SECTION 4 Questions 31-40Questions 31-35Complete the information in the table.

Lecturer: Welcome to this lecture on making houses greener. Let’s get
right into things and look at insulation first of all. Around 40% of the heat
that is lost from a home is lost through walls and the roof. The rest is lost
through the floor and openings. This figure can be significantly reduced
through the installation of simple loft insulation, which will cost between
￡130-200 to install and save around ￡150 a year in energy bills. Cavity wall     Q31
insulation costs from around ￡135 to install and can save around ￡100 a year.   Q32
Windows can be insulated by installing double glazing to reduce heat loss
through windows, although wooden frames are more preferential from an environmental
perspective than PVC.
  Now, lighting accounts for some 15% of an electricity bill. As each
energy-saving light bulb saves some ￡7 a year, the benefits are potentially        Q33
significant. On an even simpler level, ensuring that the new appliances you
install are approved by the Environmental Standards Authority means that,
for example, on a fridge, you can reduce its energy consumption by two
thirds—saving you ￡35 a year. In particularly dark areas of the upper storeys
of homes, a light-pipe might be an effective alternative to constant artificial
lighting—light is captured from the roof and channelled down a mirrored
tube. They cost between ￡200-700, depending on size and distance from        Q34
roof.
  As regards heating water, a high-efficiency condensing boiler—particularly
one that uses weather compensation control—will save you around
￡180 a year, while simply adding a jacket and lagging to the hot water cylinder           Q35
and pipes will cover its outlay in a year.
  Now, let’s look at energy generation. People are becoming increasingly
interested in generating electricity at home. PV cells are perhaps the best
known form of renewable energy and operate by turning solar radiation into
electricity. The average UK home could generate around half of its own electricity
through this method, providing it is used efficiently and the home has                    Q36
a large south-facing roof. The greater the intensity of the sunlight, the greater
the amount of electricity produced. Payback times on PV systems vary but
are usually considered to be at least 10 years. Straightforward solar panels,
which simply use the sun to heat water, tend to offer a much shorter payback
period.
  Using the wind to produce energy is becoming a viable option for individual
dwellings. The Swift Rooftop Wind Energy System is just 1.6m in                       Q37
diameter and costs around ￡1,300—it generates around 1.5kWh of energy
every time it turns. An alternative is the Windsave, which operates from the
ground and requires a pole, but the manufacturers claim the ￡1000 system
can save a third of your annual electricity costs, giving a payback time of
around five years.
  Ground source heat pumps are also becoming a realistic alternative.
The temperature at around 5-10 metres underneath the ground surface is at
a constant level of around 10℃. This heat can be extracted using the same
technology as is used in domestic fridges to provide up to four units of energy              Q38
for every one unit of electricity used to power the system. Installation
costs are between ￡8,000-12,000. Most experts give the payback time at
around ten years.
  It might be worth installing air circulation systems if the house is undergoing
extensive structural renovation. The key to such systems is a heat
exchanger, usually installed in the roof. This unit draws air from the moist
areas of the house—the kitchen and bathrooms—and expels it through the
heat exchanger. At the same time cold air from the outside is drawn in and
warmed by the heat in the outgoing moist air. This Warm air is then transferred
to the bedrooms and living areas. The best heat exchange units claim                      Q39
to be able to recover about 90% of the heat that would otherwise be deposited outside.
Installing all the ducting necessary to make systems like this
work can be tricky and messy when the job is a retrofit. However, when this
takes place in a house that is having a total refurbishment, it is unlikely to
cause more disturbance than there is already.
  Now, let’s turn to reducing water consumption. Although water bills
are still relatively cheap in the UK, last winter’s drought and this summer’s
imminent water shortages have brought the focus back on to the way domestic
properties use water. All new builds are now required to install a water
meter rather than pay a flat rate charge—and renovators interested in cutting
their consumption would do well to follow this measure, as well as installing
low-flush WCs and simple showers, rather than power showers—which                Q40
use around 20 litres of water a minute. Even when compared to a bath, which
uses around 100 litres in total, power showers are very high in usage and
those interested in conserving water should consider avoiding them. Fitting
flow restrictors might be an alternative.
For those contemplating a more significant renovation scheme, the installation of a rainwater harvesting system should be considered, as it can potentially  reduce a household’s water consumption by around half. Rainwater harvesting systems, which cost around ￡3-3,500 installed, recycle rainwater and use it to flush toilets, water gardens and for the washing machine.