P1 Revision Booklet

Thermal Energy 

Easy (Grade D/E)

Q1.          The diagram shows where heat is lost from a house that is not insulated.

(a)     (i)      Through which part of the house is most heat lost?
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(1)

(ii)     How can the heat loss through the windows be reduced?
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(1)

(b)     A homeowner wants to reduce her energy bills and make her home more energy efficient. The table shows five ways this could be done. The table also shows how much money each way would save the homeowner each year.
 
 	Cost	Money saved
each year	
Installing loft insulation	£175	£60	
Fitting draught-proofing	£45	£20	
Installing cavity wall insulation	£300	£80	
Adding a hot water tank jacket	£15	£20	
Using energy efficient light bulbs	£60	£30	

(i)      Which one of the five ways of reducing energy bills would reduce the yearly energy bill the most?
...............................................................................................................
(1)

(ii)     This year the homeowner has only got £60 to spend to improve the energy efficiency of her home.
Use the information in the table to explain what the homeowner should spend this money on.
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(2)
(Total 5 marks)
 Q2.          The diagrams show the cross-section of three double glazed windows.

The gap between the two sheets of glass can be filled with either air or a mixture of air and argon.

The U-values for different types of double glazed windows, using different types of glass 
X and Y, are given in the table.
 
 	Type of window	12 mm gap	16 mm gap	20 mm gap	
1	Glass type X with air	2.9	2.7	2.8	
2	Glass type X with air and argon	2.7	2.6	2.6	
3	Glass type Y with air	1.9	1.8	1.8	
4	Glass type Y with air and argon	1.6	1.5	1.5	

(a)     Which type of window, 1, 2, 3 or 4 is the least energy efficient?
........................................................................................................................
(1)

(b)     Which two windows should be compared to decide if adding argon to the gap improves the energy efficiency of the window?
........................................................................................................................
(1)

(c)     A householder is going to buy new windows. The sales assistant recommends that the householder buys windows with a 20 mm gap. These windows are much more expensive than those with a 16 mm gap.
It is not worth the householder paying the extra cost to buy 20 mm windows rather than 
16 mm windows.
Explain this in terms of energy efficiency.
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(2)

(d)     Windows are given an energy rating, from A down to G. The diagram shows the energy label from one type of double glazed window.

All new double glazed windows must have an energy rating of C or above.
Windows having a C rating have a U-value of 1.9.
Which windows given in the table would the householder be unable to buy?
........................................................................................................................
(1)

(e)     Glass transmits infrared radiation and visible light. The amount transmitted depends on the type and thickness of the glass. The data from tests on two different types of glass is displayed in the graph below.
          
A homeowner has a glass conservatory built on the back of the house. The homeowner tells the builder that the inside of the conservatory should stay as cool as possible throughout the summer.
Explain why the builder uses ‘Type B’ glass for the conservatory.
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(2)
(Total 7 marks)

 
Q3.          (a)     The graph shows the temperature inside a flat between 5 pm and 9 pm. The central heating was on at 5 pm.

(i)      What time did the central heating switch off?
...........................................................................................................................
(1)

(ii)     Closing the curtains reduces heat loss from the flat.
         What time do you think the curtains were closed?
...........................................................................................................................
Give a reason for your answer.
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(2)

(b)     Less heat is lost through double-glazed windows than through single-glazed windows.

          Complete the following sentences by choosing the correct words from the box. Each word may be used once or not at all.
 
conduction	conductor	convection	evaporation	insulator	radiation	

Air is a good ........................................... . When trapped between two sheets of glass it
reduces heat loss by .......................................... and ....................................................
(3)

(c)     The table gives information about three types of house insulation.
 
Type of insulation	Cost to
install	Money save each
year on heating bills	Payback time	
Double glazing	£4000	£200	20 years	
Loft insulation	£300	£100	3 years	
Cavity wall insulation	£600	£150	 	

(i)      Use the information in the table to calculate the payback time for cavity wall insulation.
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(1)

(ii)     Explain why people often install loft insulation before installing double glazing or cavity wall insulation.
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(2)
(Total 9 marks)
 Q4.          People do a number of things to reduce the energy loss from their homes.
          (a)     Describe one thing they may do to cut down the energy loss through:
(i)      the roof;
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(1)

(ii)     the outside walls;
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(1)

(iii)     the glass in the windows;
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(1)

(iv)    gaps around the front and back doors.
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(1)

(b)     A house is more difficult to keep warm in cold weather. What other type of weather makes it difficult to keep a house warm?
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(1)
(Total 5 marks)
 
Thermal energy transfer-Mark scheme

M1.         (a)      (i)     walls 
accept sides (of house)
1

(ii)     fit double glazing
or
close / fit curtains / fit shutters
accept close windows
accept keep house at a lower temperature
accept fit (foam) draft excluders around the windows / in the jams
accept put plastic (film) across the windows
do not accept fit thicker glass 
1

(b)     (i)      cavity (wall insulation) 
accept the middle one
1

(ii)     fit hot water jacket and draught-proofing
both required
1

(together) saves most money
only scores if first mark scores
accept saves more than fitting (energy efficient) light bulbs
accept saves £40
accept gives the shortest payback time
an answer fit energy efficient light bulbs (on its own) gains 1 mark only
1
[5]
 M2.         (a)     1
1

(b)     3 and 4
or
1 and 2
1

(c)     U-values for the 20 mm windows are the same or higher
than those for the 16 mm windows
1
therefore the 20 mm windows are no more energy efficient
than 16 mm windows
accept so the 16 mm windows are as energy efficient as 20 mm windows
1

(d)     1 and 2
must have both and no other
1

(e)     Type B glass transmits less infrared than Type A glass
accept radiation / heat for infrared
accept Type B glass absorbs more infrared than Type A glass
1
and as infrared has a heating effect the conservatory will
remain cooler
1
[7]
M3.          (a)     (i)      7pm
accept 19.00 / 1900
1
(ii)     8pm
accept 20.00 / 2000
1
temperature drops more slowly
accept heat for temperature accept line is less steep
1

(b)     insulator
1
conduction * 
1
convection * 
 * answers can be either way around
1

(c)     (i)      4 (years)
1
(ii)     it is the cheapest / cheaper / cheap
do not accept answers in terms of heat rising or DIY
1
has the shortest / shorter payback time
do not accept short payback time
1
[9]
M4.          (a)     (i)      (insulate it) with fibre glass or foam
or felt or polystyrene beads or
rockwool or (aluminium) foil
an example must be included
do not credit loft insulation
1

(ii)     fill the cavity with fibre glass or foam
or mineral wool or polystyrene or
named liner inside wall or making
walls thicker
an example must be included
do not credit cavity wall insulation
1

(iii)     double glaze or draw the curtains or
blinds or thicker glass or secondary
glazing described
do not credit fit smaller windows
1

(iv)    put in draught excluder (or described)
or strip or description of filling gaps
or seal gaps or double glazed doors
or build porch or curtains inside door
or mat under door
do not credit just carpet
accept buy new doors
accept premise that gap is between frame and wall as well as between frame and door
1

(b)     windy or stormy or wet or snow or
rain or sleet or hail or fog or mist
do not credit frosty
1
[5]