Mainly for Students: The measuring game

The Latin motto of the Royal Institution of Chartered Surveyors is “est modus in rebus”, which translates into English as “there is measure in all things”. Surveyors are expected to know about the size and shape of things and, in turn, their utility, cost and worth. This edition’s focus is broadly about measurement and how big or small things are and a little bit about scale. The reason for this topic is that some students, especially in their first year, find it hard to guess and/or appreciate the size of things – and others may have blind spots with numbers generally. Whatever the case, it is important to build up knowledge and competence in both formally measuring or “guesstimating” the size and shape of places, spaces, buildings and their components. Let’s look at property sales ads If you stop reading this article for a moment and flick through the rest of the magazine, hard copy or digital, you will see many pages devoted to advertisements for properties for sale or letting. Quite often the advertisement will give a site size, the size of the building overall and, sometimes, its footprint. Looking at one from a previous edition, a piece of land of 1.05 acres close to a London Underground station was being sold for possible residential development. On the site was an existing one-storey building of 18,298 sq ft. So the question is: what proportion or percentage of the site does the building take up – and how big is just over an acre? If you are a first-year student, you might also be thinking: “why the heck isn’t it in metric?” Most ads are normally in both imperial (feet and acres) and metric (metres and hectares), but the property world works in both – and commercial rents are nearly always quoted in pounds per sq ft. Let’s stay with the imperial numbers and, first, you have got to know – and remember for the rest of your studies and through to being a practising surveyor or planner – that there are 43,560 sq ft in an acre. For some of you, I can imagine you thinking “43,560 – that’s an odd kind of number”. Worse still, if an acre was in an exact square, its four sides would be 208.71 ft long. (For the mathematicians among you, it is more precisely 208.71032557111301 plus a few more decimal points to be exact). Anyway, what is the answer? 18,298 divided by 43,560 = 0.42, so 42% of the site has a building on it. So why 43,560 sq ft? The origin of an acre goes back to Anglo-Saxon times, and its name derives from Old English “aecer” and the Latin “ager”, meaning field. A field of one aecer/ager/acre was the area of land that could be typically ploughed with a yoke of oxen in one day. In terms of shape, the Anglo-Saxon acre was 660ft x 66ft, though over time it became any shape of 43,560 sq ft or 4,840 sq yd (3 ft in a yard). In passing, 660ft is one furlong (and is equal to an eighth of a mile), though you may not need to refer to this very often – or at all – unless you are interested in horse racing where distances are measured in such lengths. What does an acre look like? So now we have nailed the numbers, how big is an acre in real life? The size of the pitch of the football club I support (Nottingham Forest) is 115yd x 78yd (or 345ft x 234ft, or, in metric, 105.2m x 71.3m). That amounts to 8,970 sq yd, or 80,730 sq ft and dividing it by 43,560 makes the pitch at the City Ground c1.85 acres. If you are not a football fan, you can get a feel for the size by viewing this short video of the stadium: https://www.youtube.com/watch?v=Ne7hrcCaplE. Pitches, of course, vary in size but for the Premier League they are roughly 115yds x 74yds. What about hectares? Readers should now have a better idea of an imperial acre, but what about metric hectares? A hectare is much easier to visualise and understand. If in the form of a square, it is 100m x 100m, totalling 10,000m². While roughly the length of most professional football club pitches, 100m is also, of course, the length of the classic athletic sprint race. The grid squares on Ordnance Survey maps are in metric and, on the standard Landranger and Explorer maps series, each side of a grid square is 1,000m (1km) in length. Each square on these maps, therefore, covers 100ha. How big is a car parking space? Coming right down in scale, another useful size to have in your head to guide and improve your appreciation of spatial scale is a car parking space. They are typically 2.4m wide by 4.8m long, so just over 11.5m² (disabled or family spaces are, of course, bigger, with widths of at least 3.2m). One of the practical issues that is emerging in the industry is that there has been a steady increase in the size of the average car, which can make the standard car space a tight fit. Let’s move to room sizes Some of you may well be in a purpose-built student study bedroom. How big do you think it is? Have a look and guess – and then get a tape or similar and measure it. Typical study rooms might vary between 12.5m² and 16m². If you rent a house with five or more people (which makes it a house in multiple occupation, or HMO) the government prescribes that the minimum for a one adult bedroom is 6.51m² (70 sq ft). Measure and check how big your room is compared to that. How does it compare to the average size of a master bedroom in the UK, which is around 13.4m² (twice the HMO minimum). What about food shopping? Your typical corner shop/convenience store may well be less than 1,000 sq ft (especially if it has been converted from the downstairs of a house), but can be up to around 4,000 sq ft. Discount supermarkets typically offer between 10,000 sq ft and 15,000 sq ft of selling space (some, of course, are bigger, some smaller). When you are in one next, try to get a sense of the size and dimensions, which are typically rectangular in shape. Depending on site conditions, the length is typically around twice the width. The bigger food retailers trade out of much bigger floor spaces of between 20,000 sq ft and 60,000 sq ft – even bigger if their offer is more than food. To go back to football pitches, one of the big four supermarket chains could be trading from a space equivalent to half of a pitch, or more. Metric vs imperial? There is no choice, sadly. Students, as future practitioners, have (to reemphasise, absolutely have) to be conversant and comfortable with both imperial and metric measures. So let’s briefly set out the key conversions. 1 acre = 0.405ha and 1ha = 2.471 acres 1ft = 0.305m and 1m = 3ft 3.4 in 1yd (3ft) = 0.914m and 1m =1.094yds Like learning the multiplication tables, you should learn them by heart (along with 43,560 sq ft in an acre). Handily, there is a little rough-but-helpful conversion trick between square foot and square metre. Look again at the last set of conversions above. There are 9 sq ft in a square yard. However, given that a yard is bigger than a metre and therefore a square yard is a little bigger than a square metre, there are close to 10 sq ft in 1m². 1 sq ft = 0.093m² (ie nearly 0.1m²). The other way round, there are 10.764 sq ft in 1m2. So, for a rough estimate, when going from metric to imperial, multiply by 10; and from imperial to metric, divide by 10. Given this, in approximate terms 10,000m² is roughly 100,000 sq ft. Of course, it is 107,640 sq ft more exactly, but this is roughly right to gauge the scale of an area if you are given figures in one measure and need to mentally calculate its measure in an another. Beware though, you should not use the approximate calculations on any formal report; sit down later and do the simple maths. What next? One of things you could and should do is pick places and spaces that you are familiar with and measure them. I remember one student telling me how they didn’t go to football matches and had generally little idea how big or small pitches are, but sat for three years looking out at a lake from the university library. The student decided to measure it in order to have a personal area benchmark for other big spaces – and it worked. As mentioned earlier, start with your room and then on to other things. You could do that physically with a tape, rod or digital measuring device – and also by using Digimap: https://digimap.edina.ac.uk/ You may well have used it for geography at school, but via your university, you will have free access to it. Digimap will enable you to measure the length and area of places using very simple tools – it’s an essential tool for surveyors. Finally, without looking back, how many square feet are in an acre again? Mainly for Students is edited by Paul Collins, a senior lecturer at Nottingham Trent University. He welcomes suggestions for the column and can be contacted at paul.collins@ntu.ac.uk