Tom DyckhoffYour home is the most important piece of architecture you’ll ever experience. It’s where you spend most of your life. It’s where you express who you really are. It’s where you feel most yourself. This is somebody’s home. It’s also a work of art. This is the Lost House hidden away in London’s King’s Cross and designed by the much feted British architect David Adjaye, the poster boy for sexy, up-market housing. He creates spaces that seduce by fusing a relationship between indirect light, materials and colour. This iconic house is almost totally black. Black resin floor, black walls, with no windows, but three light wells. This is the kind of home we all drool over in the glossy magazines, but you could argue that it’s spaces like this that have driven our national obsession with what a home looks like and how expensive it is. Not what it feels like, or whether it’s good for us. Does it feel like a home, or does it feel like an artwork?Suzanna WallgrenYeah, I think it feels very much like a home. I don’t mind at all to be in a piece of art. Tom DyckhoffSo then does the house rule your life? Suzanna WallgrenYes, in a way, yeah. You cannot leave things out. They will disturb the feeling of the house. Tom DyckhoffSo what are the demands that the house makes on you? Suzanna WallgrenYou have to have a certain upkeep. You have to polish the floors. You have to keep it tidy. You have to work on the concrete. It definitely requires maintenance, absolutely. Tom DyckhoffA lot of windows. A lot of window cleaning must go on here. Suzanna WallgrenYou have to keep very good friends with the window cleaner. Tom DyckhoffBut even with all this glass everywhere, the one you can’t help noticing is a lack of direct light and a pervading gloom. It’s very dark, though, as well. I mean, all the blackness. You never feel like you’re living in a bunker? Or a coffin? Suzanna WallgrenNo, I’ve heard many things, but not that. For some reason, I never felt that this is stark or very cold feel to it. It may not be for everyone. It probably is not for everyone, but for me it is, yeah, it’s very, very peaceful. Tom DyckhoffThis is a beautiful house, meticulously thought through. But I’d argue it’s a prime example of an architect as artist, making a house that rules you, instead of making a house that fulfils your needs. Most of us don’t live in a work of art. We buy places like this. You thought the Lost House was dark? Unbelievably many windows in new housing are just over half a metre squared, about the size of a pizza box. Why so small? Simple. To save money. Small windows in new homes are a real concern for Professor Foster who, for more than 25 years, has studied how a low lux or light level can effect our internal body clock. Prof Russell FosterOutside light is incredibly bright. Even in a cloudy day in London, you’ve probably got 20,000, 30,000 lux. The equivalent in your home would be 200 to 300 lux. In fact, people have argued that we live our lives in dim-dark caves. Tom DyckhoffThis is where I live. A flat built in the 1950s. And the thing I love most of all about it, the big windows. But I’m curious to see what a lack of light does to me. So Professor Foster has devised an experiment, boarding up my windows for a week to the level of a house with the smallest national average window size. Prof Russell FosterSo what we’re going to do is reduce the light probably to something like 50 or 100 lux. Still many people are living under those sort of relatively low light levels. And then see how you cope with that reduced light exposure after about a week. Tom DyckhoffIt sounds very depressing. Oh, my god, what have I let myself in for? I bought this flat for the light, and I’m going to be without it for a whole week. It feels like being in prison, and the door has just slammed shut. So this light meter will detect how much is coming in here before we put the boards up. OK, that was about 200 from this position in this room. Now it’s reading about 50. I’ve got all these different tests to do. Urine sample, that I've got to keep in the fridge and in the freezer. Fridge full of urine – that’s very nice. Blood test, got my glucose monitor. This is my sleepiness scale. It shows you how sleepy I’m feeling throughout the day. And then these ones. These are mood ratings. Do I feel calm? Do I feel sad? Horrified? Happy? Angry? Do I feel extremely angry? I feel a bit angry at the moment. I have to be honest. The whole flat feels a bit like it’s been plunged into depression. I feel like I’m living in a cave. Or like in a Goth’s bedroom or something. I really want to get out now. I really feel like I want to escape. But you know the most worrying thing for me? The most worrying thing of all at the moment? It’s these, look, my plants. I’m not even allowed to leave my home for a week. Day four, very glum and very tired. There’s this sort of gloom over the whole flat. It does smell like a gentleman’s toilet. I can’t really wait for it to end now, I think. It’s horrible. I hate it. Make it stop. Not long to go now. I feel really, really glum.Isn’t that amazing? To reacquaint yourself with the Sun after a week. I feel like I’m going on holiday, like I’m off to Saint-Tropez after a spell in the Arctic North where there’s no light. Thank goodness that’s over with. But I wonder, what was all that darkness actually doing to my body?Prof Russell FosterSo your tension and anxiety went up significantly. Tom DyckhoffWow. Prof Russell FosterYour depression and dejection went up really quite a lot, but look at this. Your vigour collapsed enormously. Tom DyckhoffI know I felt glum, and a bit blue, and a bit grumpy and so on, but to actually see the swings. Prof Russell FosterNow let’s look at the glucose levels. And I have to say, I’m a little concerned. A glucose level above six is regarded as high. And what you see is that under the dim light conditions, your morning glucose has moved from 5.7 to 6.8. Tom DyckhoffSo I’m sort of borderline diabetic? That’s not good after a week, is it? Prof Russell FosterCertainly, if that was sustained, then you’d need to bring that down below six. Tom DyckhoffShocking, isn’t it? Prof Russell FosterIt’s quite marked actually. What was really interesting, and that urine collection was worth doing, because these data are really fascinating. If you were perfectly entrained, the body clock was exactly locked on, the period of the peaks would be exactly 24 hours, but they’re not. In fact, we’ve got a period of 24.2, which is a little bit longer, which fits with the idea that the body clock is beginning to drift. Those peaks are getting a little bit later and later.Tom DyckhoffNow what is the consequence of that? Prof Russell FosterWell, what you’re getting is a tendency for internal desynchronisation. The master clock in the brain is at a slightly different point to the clocks in the liver, to the ones in the gut.Tom DyckhoffSo if I was to carry on living like this, like many people do in new homes, what would be the result? Prof Russell FosterYou’re more likely to be depressed. Tom DyckhoffBlimey. Prof Russell FosterYou are increasing your chances of immune suppression, metabolic abnormalities such as diabetes two. And, of course, all that is associated with increased levels of susceptibility to disease. Tom DyckhoffThat’s quite incredible, isn’t it. That’s quite an incredible reaction, response. Prof Russell FosterWe are an extraordinary species, and perhaps just profoundly arrogant. We think we’re independent of so much. We can do what we like, when we like. And something as trivial as the amount of light we see each day is not considered as important. Tom DyckhoffAnd yet it is. It’s fundamental. Prof Russell FosterIt’s critical. Tom DyckhoffI’m astonished by what a lack of light can do to us. Luckily for the house builders, most of us can get out for a top-up of natural light. But for those who can’t, and for all of us in winter, staying at home in a house with small windows can certainly damage your health. And it gets worse. It’s not just light they skimp on. This country is building some of the smallest homes in Western Europe, and it’s having a devastating effect. What is the unit for measuring light?What are the light levels:outside in an urban centre?in the average British home?In the programme, the presenter, Tom Dyckhoff, is tested to see how he reacts to decreased light levels. What was the light level in Dyckhoff’s home when the window sizes were reduced?What different tests are carried out on Dyckhoff and what two main things do you think they are measuring?What are the effects on Dyckhoff from living with reduced light levels for a week?What might these effects lead to if the experimental conditions continued?How could these effects be reduced for people living in conditions of low light?The unit for measuring light is the lux.The programme states that:the amount of light outside in London is between 20 000 and 30 000 luxinside the average home it is between 200 and 300 lux.In the programme, it was shown that the light levels in Dyckhoff’s home were reduced to about 50 lux when the windows were boarded up.Dyckhoff has tests on his urine and blood to determine, among other things, his glucose levels. He also completes a couple of questionnaires: one to determine how tired he feels and the other to determine his mood.The blood and urine tests measure directly how the body is responding chemically, while the questionnaires test how Dyckhoff is feeling during the experiment. Usually the two things are related, but that is not necessarily the case. So, the blood and urine tests are measuring what we call objective things (for example, things that we can accurately put a number to) and the questionnaires are measuring what we call subjective things (for example, things that we feel).After the one-week experiment, Dyckhoff’s glucose levels have gone up, his feelings of tension, anxiety and depression have all increased, his activity and vigour have decreased, and his ‘body clock’ has begun to drift, in what the tester calls ‘internal desynchronisation’. Of course, this cannot definitely be due to the decreased light levels alone – Dyckhoff was also not allowed to leave his flat for the week long experiment. So as well as being subjected to low light levels, he was also probably not getting the same amount of exercise and social interaction as normal – which is likely to have also contributed to his increases in anxiety, depression, etc. and his metabolic changes.If the experimental conditions were to continue, Dyckhoff might be more likely to develop diabetes, suppression of the immune system, increased susceptibility to disease and depression.One way to reduce the effects would be to spend more time outside in the open, where light levels are highest. A good walk is a cure for a lot of things!Measuring lightActivity 2 Measuring lightAllow about 15 minutesDo you think the light levels in your home are above or below average? If you have a smart phone you can download a free light meter app, such as ‘whitegoods’. Then, to calculate an average value you could take readings at midday, and in the centre of every room in your home. Add these readings together and divide by the total number of rooms to reveal a good estimate of the average levels of light in your home.
Figure 1 A smartphone displays the ‘whitegoods’ light meter app
A photograph of a hand holding a smartphone with the ‘whitegoods’ light meter app showing.Measuring the average light in your home is not as straightforward as perhaps the programme leads you to believe. There are some dark places (for example, your cellar) as well as very light places (for example, by a south-facing window). Light levels would also depend on when you took your light readings, as the intensity and quality of light changes through the day.3 Here comes the SunThe most basic purpose of the place that we call home is to provide accommodation that shelters us from the rigours of the natural environment. The natural environment is often inhospitable, or certainly less comfortable than most people prefer: it is frequently too hot, too cold, too wet or too humid. This suggests that there is some kind of ‘comfort zone’ within which people prefer to live: a zone of limited ranges for the various aspects of climate that humans are capable of sensing, such as temperature. The ‘comfort zone’ of a home can be influenced by several basic things, including its overall shape, the materials used in its construction and its orientation. In this section we will concentrate on the last of these, the orientation of the building.Temperature and comfortActivity 3 Temperature, warmth and coolnessAllow about 5 minutesWe tend to think of somewhere comfortable as being somewhere that is warm in the winter and cool in the summer. What do you think the differences are between temperature, on the one hand, and warmth or coolness, on the other?Many people argue that these are the same thing, but you might think there is a significant difference. We usually think of temperature as a simple number that provides a measurement of the hotness or coldness of something. Warmth and coolness, on the other hand, have a feeling and value associated with them, especially in the context of a home. Warmth in the winter and cool in the summer makes us feel good, while temperature just ‘is’. Designers often make use of this distinction in their work. They aim to create a home that is warm or cool – and that can be done in a combination of ways, including the use of colour and materials – rather than a home that operates at a certain temperature.It is in fact very difficult to reach universal agreement on the meaning of ‘comfort’; usually the best that can be done is to define it as an absence of discomfort. Discomfort is to be, for example, too hot or too cold. There are also considerable differences between the levels at which people begin to feel uncomfortable. For Europeans, the comfort range for air temperature is about 18 to 24 °C. However, what is ‘comfortable’ also depends very much on what you are doing at the time; strenuous physical activity needs a much lower air temperature for comfort than sitting in a chair. Figure 2 shows in very simplified form the ‘comfort zone’ for sedentary activity, in terms of temperature and humidity.
Figure 2 The ‘comfort zone’ in terms of temperature and humidity for sedentary activity and people’s subjective responses to various climatic conditions outside that zone
This is a graph showing the comfort zone in terms of temperature and humidity for sedentary activity.The x-axis indicates relative humidity as a percentage from 0 to 100 in increments of 10.The y-axis shows temperature in °C with a range of 0-35 in increments of 5.The following areas on the graph are separated by dotted lines and labelled follows:0–40% humidity and 0–18 °C is ‘keen’.0–40% humidity and 18–24 °C is too dry.0–40% humidity and 24–35 °C is ‘dry heat’.40–70% humidity and 0–18 °C is too cold.40–70% humidity and 18–24 °C is labelled with a cartoon of someone sitting comfortably in an armchair indicating the ‘comfort zone’.40–70% humidity and 24–35 °C is too warm.70–100% humidity and 0–18 °C is ‘raw’.70–100% humidity and 18–24 °C is too humid.70–100% humidity and 24–35 °C is ‘sultry’.Obviously the UK temperature will sometimes fall within the comfort zone shown in Figure 2, and (if the other factors that influence comfort, such as air movement, are also within comfortable limits) at these times it is quite possible to be comfortable out of doors without any shelter. However, as you will probably know, in the UK, the number of days in a year in which all the comfort factors are satisfied is actually rather few. So, for a comfortable life, shelter from the elements is needed for most of the year in UK. A simple shelter would provide some protection (principally against wind and rain) and would be adequate for the few summer months, but for the rest of the year not only is shelter needed but also some more active forms of modifiers of the climate, particularly some form of heating.Heating a homeHow do you heat your home? A quick answer might be: with central heating! You might well be right, of course, but there is another major source of heat in the home and that is the Sun. You may have noticed that some homes, or some rooms in a home, are more of a ‘sun-trap’ than others. This is because their orientation (particularly that of their windows) towards the Sun means they pick up significant quantities of solar heat on sunny days. This is called ‘solar gain’ and it has become an increasingly important factor in the design of new homes.Activity 4 Heat from the SunAllow about 5 minutesCan you think of any ways in which the Sun can provide heat to a home?The Sun can provide heat in two ways: a direct way, when sunshine heats up rooms as described above, and an indirect way, when solar panels convert the Sun’s energy into electricity or hot water that can then be used to power heating systems.
Figure 3 Modern houses fitted with solar panels
A photograph showing modern houses with solar panels on the roofs.At present, the majority of homes in the UK do not have solar panels installed, though that is slowly changing due to government initiatives in renewable energy (energy that comes from natural and infinite sources like the Sun, wind, and the sea without the need to burn and use up valuable fuel). At the moment most people will only experience the direct effect of the Sun in their homes.Activity 5 Other sources of heatAllow about 5 minutesApart from the heating system that you have in your home – solar powered or otherwise – can you think of any further sources of heat?People give off heat, and the more of them you can fit into your home the less you will need other sources of heat, as you may have noticed at a crowded party. Household appliances are also incidental sources of heat. A refrigerator, for example, gives off some incidental heat, as do computers, television sets and other electrical appliances. Cooking also gives off heat, as do lights.4 What is your orientation?A critical determinant for how much heat a building needs is its orientation in relation to the Sun. A building that faces the Sun without any obstruction – a south-facing house with an unobstructed view of the sea, for example – will be much warmer than one that doesn’t. Remember, however, that the position of the Sun changes throughout the day, so a house that faces the Sun in the morning might not necessarily face the Sun in the evening.Usually, though, the orientation is determined by many other factors: the need to fit a number of buildings on a restricted site, the need to link with roads and other existing networks, the need to take into account the surrounding landscape and other buildings. For example, if houses are built in terraces on either side of a road, one side will always get more Sun than the other side.Activity 6 Sunlight and orientationAllow about 5 minutesTake a good look at the picture below, which shows a bird’s eye view of streets and buildings. The image is oriented so that the top points north, the right-hand side points east, the bottom points south, and the left-hand side points west. Which way do you think the Sun is shining? Where do you think the sunniest house in the picture is, and where do you think the least sunny house is?
Figure 4
The picture shows a bird’s-eye view of an area of a city with north at the top. There are twelve or so blocks of buildings and open space with roads running horizontally and vertically between them in a grid pattern.The horizontal roads run diagonally across the picture from south-west to north-east. The vertical roads run from north-west to south-east.Buildings are represented as cuboids of varying dimensions. Some buildings are oriented with their longest sides running south-west to north-east, others run north-west to south-east. Shadows are visible on the ground on the north-west side of each building.Some buildings have open space to the south-east while others are surrounded by other buildings.The sequences of pictures below answer the questions above.The best way to determine which direction the Sun is shining in is to look at shadows. If you look carefully at the first image, you can see shadows next to the north-west facing sides of the buildings, and that reveals the direction of the Sun as being from the south-east. Another telling shadow is cast by the large building next to the tennis courts, circled and enlarged in the first image below.
Figure 4a
The same image as in the question but showing an extra, enlarged version of the building near the tennis courts, to indicate where the shadows are falling.The second image shows the buildings that are likely to be the sunniest. These are the buildings which face towards the south, and which don’t have too many obstructions around them. The big building surrounded by the tennis courts and other green space is likely to have the most Sun of all.
Figure 4b
The same image as in the question, but this time with red lines around the buildings facing south with little shadow.The third image shows the buildings that are likely to be least sunny. These are east and west facing with obstructions all around them. They will get some sunlight through the day, but it will be far less than the sunniest houses.
Figure 4c
The same image as the question but this time with red lines around the buildings that are facing east and west (and which have obstructions around them) to show the buildings that have the least Sun.Building shapes and climateIt is nevertheless possible to consider the overall shape of a building and its orientation on an idealised open site and to reach conclusions about the best design that is suited to a particular climate. There are four principal types of climate: cold, temperate, hot-arid and hot-humid that lead to different forms of building (Figure 5).
Figure 5 Four basic building shapes suited to four distinct kinds of climate: (a) cold, (b) temperate, (c) hot-arid, (d) hot-humid
The elements of this figure are described in the text.In cold regions the need to conserve heat is very important and leads to trying to minimise the outer surface area of the home, in order to reduce heat loss. This minimum surface area is achieved, for example, in the hemispherical (half-sphere) form of the igloo.In temperate regions (such as the UK) a rectangular plan is desirable, with the shorter sides facing east and west. Such a home has a long southern face, which catches the Sun when it is available. Because the climate is not so extreme in temperate regions, however, more diversity in home shapes is possible in without significantly affecting heat gain or loss.In hot-arid (desert) regions the extreme conditions demand a return to a more compact shape, with the addition of special features such as internal, shaded courtyards cooled by water to help create a comfortable ‘micro-climate’ within the home and its immediate surroundings. In hot-humid (tropical forest and swamp) regions the actual temperature is usually not so excessive as in hot-arid regions, but the high humidity significantly affects discomfort. So long as the roof provides adequate shelter against rain and Sun, an open-sided elongated shape has the advantage of being able to catch any cooling breezes.The orientation of the home is obviously important for elongated shapes. Usually the dominant factor is the orientation of the main facade towards the Sun, though other factors (for example, wind direction and ease of access) can be just as, or more, important in planning the orientation of the home. In temperate regions this is a matter of trying to arrange the home shape and orientation so as to collect as much heat as possible from the Sun in winter, while avoiding overheating from solar gain in the summer. In temperate regions in the northern hemisphere the maximum summer solar gain in fact comes from a south-westerly direction, whereas the maximum winter solar gain comes from slightly east of south. These comments apply to the whole home, not just to window orientation, and to the build-up of heat during the whole day. This conveniently means that, in northern temperate regions, the optimum orientation for the longer facade is just to the east of south so as to receive the most winter warmth, thereby turning the shorter facade to the south-west, the direction of highest solar gain in summer (Figure 6).
Figure 6 The best orientation for the longer facade of a home in a northern temperate region is slightly to the east of south, to take advantage of solar gain in winter while avoiding overheating in summer
A diagram with a rectangle representing a building with a line-drawn compass showing north, south, east and west (north at the top of the image) superimposed over the top.The longer facade of the rectangle faces just to the east of south so as to receive the most winter warmth – a ‘Sun’ in the bottom right of the diagram with an arrow leading to this facade is labelled ‘maximum heat gain in winter’. The shorter facade faces the south-west, the direction of highest solar gain in summer (as described in the text). A Sun in the bottom left with an arrow pointing to this facade is labelled ‘maximum heat gain in summer’.Homes in different climates The best way to think about orientation and climate is to think about pitching a tent. Imagine different types of climate and where you’d put your tent in order to minimise the negative effects of the climate and maximise the positive effects. What is the first thing you think of when you arrive at a place to pitch a tent? If it was windy, you’d probably look for somewhere protected from the wind; if it was wet, you’d probably look for the driest place; if it was very hot, you’d probably look for somewhere that was shaded. And the fact that you have a tent probably means that you’d like a good view, so that is something else to think about! What you are doing, in actual fact, is making a design decision; balancing a number of different factors to try to work out what the best (or optimal) solution is.However good we think our solution is, though, we inevitably find that it can be improved. We might forget to think about where the Sun will come up in the morning if we are pitching our tent late in the day and wake to find we are much too hot. We might have pitched our tent at the bottom of a hill, to keep out of the wind, and wake to find it has rained heavily during the night, and that our tent is now on soggy ground. If we are staying in the same place for another night, we will alter our ‘solution’ accordingly, to further optimise our design.Activity 7 Climate and house designAllow about 5 minutesWith reference to what you have just read, what do you think a sunny, hot climate like that of the south of Spain would do to the design of houses?The climate in southern Spain tends to be hot and arid, especially during the summer months when there is a lot of sunshine and not much rain. This tends to mean that houses are designed more for shade, and the reduction of solar gain, than capturing sunlight. Southern Spain is also famous for its ‘white towns’, where houses are whitewashed to avoid absorbing heat from the Sun (white things absorb much less heat than dark things and stay cooler as a result). In general, southern Spanish houses have relatively small south-facing windows and more shaded spaces, for example by using overhangs or loggia to block direct sunlight in the summer. They also use ‘cooler’ materials, for example terracotta roof and floor tiles, and lightweight bricks that don’t retain heat.
Figure 7 Whitewashed houses in southern Spain
An aerial photograph of white houses in a village location in southern Spain. Changing the orientation of a home plan can have a major effect on how much solar heat it might gain. In one orientation a home can be overheated by the Sun in summer, yet get little or no benefit from the Sun in winter; in a different orientation the same home design can be picking up maximum solar gain in the winter, while not becoming overheated in summer.To understand how this change of orientation can be so significant, you need to know something of the Sun’s apparent movement in the sky (Figure 8).
Figure 8 The apparent movement of the Sun through the sky at (a) midsummer and (b) midwinter over the central UK
The elements of this diagram are included in the text.The Sun’s relationship to the Earth is constantly changing – through days, months and seasons, which means it is never in quite the same position. In the UK in midsummer, the Sun rises in the north-east and sets in the north-west and at midday reaches an angle overhead of approximately 60° to the horizontal. In midwinter, it rises in the southeast and sets in the south-west, and at midday reaches an angle of only 15° to the horizontal. Between midsummer and midwinter the apparent path of the Sun varies between these extremes.Activity 8 Which home for which climate?Allow about 10 minutesLook at the figures below and try to work out which home would suit the UK climate and which would suit the southern Spanish climate. Ask yourself which rooms would benefit from solar gain, and at what time of year. What function do you think the overhanging roof achieves?
Figure 9
This contains three separate diagrams labelled a,b and c.A rectangular drawing representing a house. Dining room, kitchen, bathroom and bedroom 2 are labelled as facing ‘cold north-east’ and are at the back of the house. Living room, bedroom 1 and porch are at the front of the house and labelled as facing ‘afternoon sun’.In this diagram the living room, porch and bedroom 1 are at the front of the house. The house has a loggia roof at the front. The dining room, kitchen, bedroom 2 and bathroom are at the back of the house. The front of the house is labelled as facing ‘morning sun’.This relates to figure b and is a cross-section through a house with a loggia roof. The diagram is labelled as having ‘summer sun’ restricted from coming into the building by the loggia roof, and ‘winter sun shining into the house.Figure (9a) is more suited to the UK climate and (9b) is more suited to a Spanish climate. In (9a), the living room and bedroom 1 face the south-west and gain the maximum midsummer solar heat, but in midwinter they receive light from the setting Sun too late in the day to gain much benefit from it. In (9b), the living room and bedroom 1 face the southeast and receive the morning Sun, which helps to warm the home in midwinter but which doesn’t cause them to become too hot in summer. The overhanging roof shades the main living room windows from the hottest south and south-westerly Sun in midsummer, but in midwinter the Sun is lower in the sky and therefore penetrates below the shading angle of the roof. Also, in (9b), the dining room and kitchen pick up the late-evening summer Sun in the north-west, which might be welcome, and both bedrooms receive early-morning Sun for most of the year.5 The solar centuryIn the present-day UK more and more homes are making use of solar panels to convert the Sun’s energy into electricity or hot water. This can mean cheaper bills at a time when energy is becoming an increasingly scarce resource and thus more expensive. Figure 10 shows some images of energy generation from the Sun. The size and arrangement of some of the solar arrays in the desert can be truly astounding.
(a) A photograph taken from above of approximately 50 rows of solar panels in a large open space resembling an American plain.(b) A photograph of a modern house with solar panels on the roof.(c) An aerial photograph of hundreds of solar panels arranged in concentric circles.Many new houses have solar panels built into the fabric of the building (for example those in Figure 10b, above) and it is an area that will become increasingly important in our future energy generation. The solar panel technology has been developing since the invention of photovoltaic technology (which is the technology used in solar panels that convert solar energy to electricity) in the mid 1950s and, although still expensive, is now becoming increasingly viable for meeting a home’s energy requirements. To function effectively, however, solar panels need as much direct sunlight as possible and this means that orientation is key.Activity 9 Which roof is better for solar panels?Allow about 5 minutesThe figure below shows one of the terraced streets you saw when you did Activity 6. Some of the buildings in the drawing have ‘pitched’ roofs – ones where the two sides of the roof are sloping and meet along a ridge – these are ideal for mounting solar panels. As before, north is towards the top of the figure. Look at the figure and, for two or three different houses or buildings, work out which bit of roof would generate the most electricity from solar panels. What implications does the constantly moving Sun have for solar panels?
Figure 11
This drawing shows a bird’s eye view of lots of streets and buildings. The image is oriented so that the top points north, the right-hand side points east, the bottom points south, and the left-hand side points west. The shadows in this picture are facing north-west.At the centre-right of the image are some tennis courts, and just north-west of this is a large building with a very clear shadow.You would put your panels on the part of the roof that was most south-facing. In the figure, there are no roofs that face directly south (towards the bottom of the photo) but there are plenty of roofs which face south-east or south-west. The big building at the bottom of the photo, for example, has a large expanse of roof facing south-east that would be ideal to mount some solar panels.Although solar technology has developed so that the angle of the sunlight is less important, the more direct the sunlight – the more it falls at a 90° angle (a right-angle) onto the solar panel – the better. This means that solar panels that ‘track’ the Sun as it moves through the sky could potentially generate more energy. Imagine, for example, a field of sunflowers, and how the head of each sunflower moves to face the Sun right through the day to capture as much Sun as possible.A drawback might be that the energy used by the tracking system would detract from the energy generated as well as needing more maintenance, so in practice what’s called a ‘static array’, provided it is south-facing, is the cheapest and most efficient.Activity 10 Katie’s houseAllow about 10 minutesKatie’s house has a south-facing roof on one side. The dimensions of the roof panel facing south are 5 m (length) and 6.5 m (width).
Figure 12
This is a diagram of two rectangles, one set inside the other.The larger rectangle has dimensions of 5 metres by 6.5 metres.The dimensions of the smaller rectangle are not shown but there is a gap of 0.5 metres between the two rectangles on all sides.Question 1What is the area of the south-facing roof panel?Katie has been advised to leave a 0.5 m border around the edge of her roof as shown in above. What area is available for solar panel use?The area of the south-facing roof is 6.5 m × 5 m = 32.5 m2.5 m – (2 × 0.5 m) = 4m.The length of the rectangle in which solar panels can be fitted is 4 m.Similarly the width of the rectangle is 5.5 m.This gives an area of 4 m × 5.5 m = 22 m2.Question 2The roof panels Katie is looking at measure 1.6 m (length) by 0.9 m (width). The panels fit exactly next to each other with no overlap or gap. The panels have to be fixed so their length is along the length of the roof.How many panels can Katie fit in the available space on her roof?Find the area of a roof panel. Explain why your answer to part (c) is not the same as the calculating the area of the roof space available divided by the area of a roof panel.Each panel gives 200 watts (W) of power. Using your answer to part (c), find out how much power Katie will get from her solar panels. Give your answer in kilowatts (kW) to 1 d.p. The watt is the SI unit for power, and a kilowatt is 1000 watts. Hence to convert from W to kW, divide by 1000.The panels stay in the same orientation.5.5 m ÷ 0.9 m = 6.111.Across the width we can fit 6 panels.4 m ÷ 1.6 m = 2.5In the length we can fit 2 panels. This means there is room for 12 panels on the roof altogether.Find the area of a roof panel. 1.6 × 0.9 = 1.44 m2. Divide the available roof area by the panel area. 22 ÷ 1.44 = 15.3 (1 d.p.).The difference arises because we round the values for the length and width before multiplying in the first case. We can’t use bits and pieces of panels to cover the area but can only work in whole panels.There are 12 panels each giving 200 W of power. 200 W × 12 = 2400 W.So we get 2400 W of power in total. To convert to kilowatts (kW), divide by 1000.2400 W ÷ 1000 = 2.4 kW.So, the system will give 2.4 kW of power.Study note: information from figuresActivity 11 Information from figuresAllow about 10 minutesLook back over Figures 2, 5, 6 and 8. Think about the nature of each figure – what kind of information or idea is it conveying? See if you can understand the significance of each illustration and how it relates to the ideas developed in the text. Consider why these figures have been included, and whether it might have been possible or preferable to have conveyed the ideas in words.Each of the figures in this section is of a different type, although several of them may look rather similar.The first, Figure 2, conveys in a simple visual form a lot of data and related information about people’s responses to temperature and relative humidity. To convey the same information in words would have meant a lengthy and complicated piece of text, and it’s almost certain that you would not have grasped the information as readily as you can from the illustration. Notice how the shaded area implies that the ‘comfort zone’ is less well-defined than might be suggested by the rigid rectangle enclosed by the dotted lines. The drawing inside the zone also implies the kind of activity for which this zone is ‘comfortable’.Figure 5 is a different kind of illustration. It doesn’t really convey any more information than the article it accompanies, but it shows examples of the types of building forms that are outlined in the text. It therefore makes the text easier to understand. You might also find the pictures easier to remember than the words in the text.The next illustration, Figure 6, is a graphical representation of some principles that are also explained in the text. The drawing enables you to literally ‘see’ what the author means; how the two important orientations happen to come conveniently at right-angles to each other.Figure 8 is a visualisation of something that happens in three-dimensional space and time – the apparent motion of the Sun through the sky. Once again, the illustration easily conveys something that is much more difficult to convey with words alone; and it helps you to understand the text.The figures are not there just to make the website look more attractive! Since technology is so often about real-world objects, illustrations are used in technology courses to explain those objects, and also to help you to ‘visualise’ the ideas connected with those objects.Your home’s orientationActivity 12 Your home’s orientationAllow about 1 hourThe purpose of this activity is to help you to work out how well the place where you live has been shaped and oriented to take account of the Sun’s apparent movement around it. If you like, you can choose another building that isn’t your home for this activity.For this activity you will need three different coloured pens, as well as a compass or something else to draw large circles with, a pencil and some paper.Draw out the shape of your home as if a bird was looking down on it from above. You might like to use the satellite view in Google Maps to help you: magnify it as much as you can and print it out if you need to. Try to get a sense of the proportions of your home in order to draw its shape. Make a double line for walls that have windows in. See below for an example, which is a terraced house.
Figure 13
A rectangular shape with the short end at the top of the picture. A smaller rectangle shape has been cut out of the right hand corner of the image, so that the rectangle is incomplete.Establish where north is in relation to your home. The simplest way to do this is to use Google Maps, which has north at the top of the screen, but you could also use a compass, or observe where the Sun is at midday (13:00 in British Summer Time), which will always be south.Draw a north–south line through the middle of your home, and then draw the corresponding east–west line through the same point as shown below.
Figure 13a
The same ‘drawing’ but with an added cross drawn diagonally across the rectangle representing a compass. North is at the top right of the diagram, east is bottom right, south is bottom left and west is top left.You now need to draw lines that show approximately where the Sun rises and sets in summer and in winter. To do this, imagine that the north–south and east–west lines have turned, like a wheel, through 45°. Draw these lines, in a different colour, through the centre of your home as shown below.
Figure 13b
The same diagram as above but with a further cross (coloured blue) drawn from top to bottom and left to right.Next, using a compass, or by holding a bit of string tied to a pencil, lightly draw two large concentric circles from the centre of your home all around it as shown below.
Figure 13c
The same diagram as above but with two light concentric circles drawn over the imageYou now need to draw a line that represents sunrise (towards the east) to sunset (towards the west) in midsummer. With a red pen or pencil, trace the outer circle clockwise from 45° on the east side of north to 45° on the west side of north. Next, draw a line that represents sunrise to sunset in midwinter. With a yellow pen or pencil, trace the inner circle clockwise from 45° on the east side of south to 45° on the west side of south. Your drawing should now look like this: