The Trombe Wall: Heating Buildings with Sunlight: Reading Answers & Explanations
IELTS Reading practice test · 14 questionsAcademichard
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About this passage
The passage opens: “On a hillside at Odeillo, in the French Pyrenees, stands a row of houses whose southern faces are almost entirely dark glass. They were built in the 1960s by the engineer Félix Trombe and the architect Jacques Michel, and they heat themselves, in large part, with nothing more elaborate than a wall.”
- Passage length: about 746 words
- Questions: 14
- Question types: Flow-Chart Completion, Diagram Label Completion, Multiple Choice, Yes / No / Not Given
“The Trombe Wall: Heating Buildings with Sunlight” is an original IELTS-style practice passage written by IELTS-Bank. It is not taken from an official IELTS or Cambridge test, so these answers only apply to our version.
Answer key at a glance
The Trombe Wall: Heating Buildings with Sunlight answers with explanations
Questions 1–4: Flow-Chart Completion
How a Trombe wall heats a room during the day
Complete the flow-chart below. Choose NO MORE THAN TWO WORDS from the passage for each answer.
- 1
Flow-chart gap 1 — Sunlight passes through the outer sheet of ______ and strikes the wall.(max 2 words)
Show answerHide answer
Answer: glazing (also accepted: glass)
Why: Paragraph 3 says "Sunlight passes through the glazing and strikes the black surface"; paragraph 2 describes the sheet of glazing fixed in front of the wall.
Where to find it · Paragraph 2 “Its outer face is coated with matt black paint so that it absorbs as much sunlight as possible, and a sheet of glazing, of single or double glass, is fixed a few centimetres in front of it, sealing off a narrow cavity of trapped air.”
- 2
Flow-chart gap 2 — The dark surface absorbs the radiation, heating the air trapped in the narrow ______.(max 2 words)
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Answer: cavity
Why: Paragraph 2 explains the glazing seals off "a narrow cavity of trapped air", and paragraph 3 says the air in this cavity can reach sixty degrees.
Where to find it · Paragraph 2 “Its outer face is coated with matt black paint so that it absorbs as much sunlight as possible, and a sheet of glazing, of single or double glass, is fixed a few centimetres in front of it, sealing off a narrow cavity of trapped air.”
- 3
Flow-chart gap 3 — The hot air rises and streams into the room through the ______.(max 2 words)
Show answerHide answer
Answer: upper vents
Why: Paragraph 3 states the hot air "rises, and streams into the room through the upper vents".
Where to find it · Paragraph 3 “Being hot, it rises, and streams into the room through the upper vents, while cooler air near the floor of the room is drawn out through the lower vents into the bottom of the cavity to be heated in its turn.”
- 4
Flow-chart gap 4 — Cooler air near the floor is drawn back to be heated again, forming a continuous ______.(max 2 words)
Show answerHide answer
Answer: convective loop (also accepted: loop / thermosiphon)
Why: Paragraph 3 calls the result "a continuous convective loop — engineers call it a thermosiphon".
Where to find it · Paragraph 3 “The result is a continuous convective loop — engineers call it a thermosiphon — that carries warmth into the building all afternoon without a single fan.”
Questions 5–8: Diagram Label Completion
Cross-section of a Trombe wall
Label the diagram below. Choose NO MORE THAN TWO WORDS from the passage for each answer.
- 5
Diagram label 1 — a projecting roof ______ that shades the glass from the high summer sun(max 2 words)
Show answerHide answer
Answer: overhang (also accepted: roof overhang)
Why: Paragraph 4 describes "a projecting roof overhang above the glazing" that shades the wall from the high summer sun.
Where to find it · Paragraph 4 “Summer brings the opposite problem, and the classic remedy is architectural rather than mechanical: a projecting roof overhang above the glazing shades the wall from the high summer sun while leaving it exposed to the low sun of winter, and additional vents at the top of the cavity can be opened to the outside so that unwanted hot air is dumped there rather than indoors.”
- 6
Diagram label 2 — an insulated ______ that is lowered over the glass after dark(max 2 words)
Show answerHide answer
Answer: shutter (also accepted: insulated shutter)
Why: Paragraph 4 says "an insulated shutter is also lowered over the glazing at night" to cut heat losses through the glass.
Where to find it · Paragraph 4 “In careful designs an insulated shutter is also lowered over the glazing at night, cutting the heat that would otherwise be lost back through the glass.”
- 7
Diagram label 3 — the coating of matt ______ on the outer face of the wall(max 2 words)
Show answerHide answer
Answer: black paint
Why: Paragraph 2 says the outer face "is coated with matt black paint so that it absorbs as much sunlight as possible".
Where to find it · Paragraph 2 “Its outer face is coated with matt black paint so that it absorbs as much sunlight as possible, and a sheet of glazing, of single or double glass, is fixed a few centimetres in front of it, sealing off a narrow cavity of trapped air.”
- 8
Diagram label 4 — a massive wall built of brick, stone or ______(max 2 words)
Show answerHide answer
Answer: concrete
Why: Paragraph 2 states the wall is "built of brick, stone or concrete, materials chosen for their capacity to store large quantities of heat".
Where to find it · Paragraph 2 “On the side of the building that faces the winter sun — the south side, in the northern hemisphere — a massive wall is built of brick, stone or concrete, materials chosen for their capacity to store large quantities of heat.”
Question 9: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. He was the first person to think of warming a wall behind glass.
- B. He turned an earlier, forgotten idea into a practical system.
- C. He patented the design in 1881.
- D. He discovered how glass traps heat.
- 9
Why does the design bear Félix Trombe's name?
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Answer: B — He turned an earlier, forgotten idea into a practical system.
Why: Paragraph 1 notes Edward Morse patented the idea in 1881 but it was "promptly forgotten", and that Trombe and Michel "turned the curiosity into a working system".
Where to find it · Paragraph 1 “The idea was not strictly new — a patent for a glazed, sun-warmed wall had been granted to the American inventor Edward Morse as early as 1881, and promptly forgotten — but it was Trombe and Michel who turned the curiosity into a working system, and it is Trombe's name the design now bears.”
Question 10: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. to stop the air circulation running in reverse
- B. to keep dust out of the cavity
- C. to stop the wall releasing its stored heat too quickly
- D. to protect the glazing from frost damage
- 10
According to the passage, the vents must be closed at night
Show answerHide answer
Answer: A — to stop the air circulation running in reverse
Why: Paragraph 4 warns that otherwise "the circulation reverses, and air chilled against the cold glass sinks and pours back into the room".
Where to find it · Paragraph 4 “The vents must be closed after dark; otherwise the circulation reverses, and air chilled against the cold glass sinks and pours back into the room.”
Question 11: Multiple Choice
Choose the correct letter, A, B, C or D.
- A. It stores heat from the summer for use in winter.
- B. It prevents the cavity from becoming too hot.
- C. It delivers warmth indoors in the evening, when it is most needed.
- D. It removes the need for an insulated shutter.
- 11
Why is the wall's time lag described as valuable?
Show answerHide answer
Answer: C — It delivers warmth indoors in the evening, when it is most needed.
Why: Paragraph 4 says heat collected at midday "reaches the interior surface in the evening, just as the outside temperature is falling and the rooms most need it".
Where to find it · Paragraph 4 “Heat collected at midday reaches the interior surface in the evening, just as the outside temperature is falling and the rooms most need it, and the wall then radiates gently into the room for much of the night.”
Questions 12–14: Yes / No / Not Given
Do the following statements agree with the claims of the writer?
Write YES if the statement agrees with the claims of the writer, NO if the statement contradicts the claims of the writer, NOT GIVEN if it is impossible to say what the writer thinks about this.
- 12
A Trombe wall is a poor choice in places where winters are consistently cloudy.
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Answer: YES
Why: Paragraph 5 says that in persistently cloudy regions "the case is far weaker", the wall becoming little more than a poorly insulated slab of cold masonry.
Where to find it · Paragraph 5 “In persistently cloudy regions the case is far weaker, for a wall that receives little sun spends much of the winter as nothing more than a poorly insulated slab of cold masonry.”
- 13
The main attraction of a Trombe wall is its low construction cost.
Show answerHide answer
Answer: NO
Why: Paragraph 5 states a Trombe wall "is not especially cheap to build, and its appeal lies less in economy than in simplicity and endurance".
Where to find it · Paragraph 5 “Nor is money the design's real attraction: a Trombe wall is not especially cheap to build, and its appeal lies less in economy than in simplicity and endurance — there is nothing to break down, nothing to service and nothing to replace.”
- 14
Governments ought to encourage passive solar design in new housing.
Show answerHide answer
Answer: NOT GIVEN
Why: The writer assesses where the design works well but expresses no view about government policy or encouragement.
Closest related text · Paragraph 1 “The Trombe wall belongs to the family of 'passive' solar designs, which are distinguished from solar panels and heat pumps by having no moving parts, no fluids to circulate and nothing that draws electricity: the building itself is the machine.”
Estimated band score for this test
Your raw score out of 14 scaled to the 40-question IELTS Reading (Academic) conversion table. This is the same estimate the practice page shows after you submit. A single passage is a small sample, so treat it as a guide.
| Correct answers | Estimated band |
|---|---|
| 14 / 14 | 9.0 |
| 13 / 14 | 8.5 |
| 12 / 14 | 7.5 |
| 11 / 14 | 7.0 |
| 10 / 14 | 6.5 |
| 8–9 / 14 | 6.0 |
| 7 / 14 | 5.5 |
| 6 / 14 | 5.0 |
| 5 / 14 | 4.5 |
| 4 / 14 | 4.0 |
| 3 / 14 | 3.5 |
| 2 / 14 | 3.0 |
| 1 / 14 | 2.0 |
| 0 / 14 | 0.0 |
Full-test score? Use the IELTS band calculator.
Tips for the question types in this test
Flow-Chart Completion
- Read the chart title and skim every box before searching the passage, so you know what process is being described and which details are missing.
- Note the word limit and, if there is a lettered word bank, whether options can be reused.
Common trap: Filling a box with a detail from the wrong stage — neighbouring steps often mention similar objects or actions.
Full Flow-Chart Completion strategyDiagram Label Completion
- Study the diagram first: read its title, the labels already printed, and where each empty label’s arrow points — printed labels are your anchors in the text.
- Note the word limit before writing anything.
Common trap: Labelling a nearby part instead of the one indicated — arrows are precise, and the examiner places similar components close together.
Full Diagram Label Completion strategyMultiple Choice
- Read the question stem carefully before the options so you know exactly what is being asked.
- Because multiple-choice questions follow passage order, locate the relevant section and read it in full — the answer usually depends on more than one sentence.
Common trap: Distractors that use exact words from the passage but distort the meaning.
Full Multiple Choice strategyYes / No / Not Given
- Identify the claim in the statement and, crucially, whose opinion it represents — these passages often quote several people, so track who is speaking.
- Scan the passage for opinion signals: verbs like "argues", "believes", "suggests", "claims", and phrases such as "in the author’s view".
Common trap: Treating a reported opinion (someone else’s view mentioned by the writer) as the writer’s own conclusion.
Full Yes / No / Not Given strategyPractise “The Trombe Wall: Heating Buildings with Sunlight” under exam conditions
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