I have the impression that many people today look at building as a quite complicated thing. Some expect a creative genius to provide a brandnew solution; others look in vain for the means to break the seemingly vicious circle of tradition.

I fully believe in commonsense which tells us that because component building has been good for ages, it might still be so-whether the job at hand is a simple wooden hut with simple wooden windows surrounds, or a magnificient public building with glorious marble window surrounds. It is, by the way, quite unnecessary to try to define what a component is. There are small and big ones, some are more prefab than others. The main thing, in my opinion, is to try to expand from using the components we have been using for so long, such as basins, windows, and doors, to using components for the rest of the house. In my own country, Denmark, we were very lucky when we attempted this component approach.

We started with a national law. This law made it possible to put provisions which furthered the use of prefab components into building regulations. Regulations which require that rental housing shall be planned in agreement with modular rules for building set forth in some Danish standards are based on this law. Please note that the first step of modular dimensional coordination (in Denmark) was only made compulsory for rental housing. The standards referred to state that we have a basic building module (M), equal to 100 millimeters, and we have a planning module of 3 M. That's all. So, the interpretation of this stipulation of the building requirements was left

rather free.

We have chosen to understand the building act to mean that projects must be designed so as to assure that the greatest possible number of modular components may be used. It is not modular coordination for its own sake, it is modular coordination because we want to use as many prefab modular components as possible.

Editor's note: The illustrations used by Mr. Blach are not reproduced and the transcript of his remarks has been edited to eliminate references made to slides. The editor takes full responsibility for any lack of clearness that may have resulted therefrom.

We say that projects must be modular. We can require that, but we cannot require that everyone use modular components. The kind of component which will finally be used is chosen after economy has been considered. In quite a few cases it may be more economical, for example, to pour concrete instead of using prefab concrete components. We can only require that the project be modular, so that we may use modular components.

In this connection, I should like to add that there is a further reason for sticking to this formulation. We have found in larger projects that there is often a 10-year period from the moment someone gets the idea to build until the last tenant has moved in. During this time, quite considerable changes may occur in design, construction methods, and also economic relations to design. We have had many cases already where the first 100 or 200 apartments were cheaper when quite conventional building methods were used, and the second, third, and fourth stages were cheaper when prefab components were used. In this type of situation, where changes had to be made after we were underway, it is quite evident that we saved a lot of money by having required that projects be modular. This means mainly, that we are able to change easily and substitute something made onsite with a modular prefab component. If the project is not modular, we have to redesign the whole project to do this.

In plain language, our main aim is to use as many catalog components as possible. Achievement of this aim has been facilitated by the fact that there is a tradition in Denmark for using components. About 800 years ago, our old farmhouses were constructed with precut pieces of timber. So, what we are doing today is really much the same-component catalog building. Only today we are doing component building under quite new industrial conditions.

About 25 or 30 years ago in Denmark, just before the outbreak of World War II, an all-around architectengineer knew by heart about 300 materials and constructions. It is difficult to define exactly what is meant by a material or construction, but he had about 300

possibilities to choose from. When we checked again, just after World War II in 1947, the number of possi bilities had gone up considerably to more than 4,000. The next time we checked, it had gone up to 15,000, and the last time we were able to check, even in a small country such as Denmark, it was past 100,000 possibilities.

Where we are today, I do not know. With the new possibilities provided by light metal alloys and by plastics, we must have passed a quarter of a million possibilities. At the same time, production and other conditions have undergone radical changes. For example, building materials research has changed considerably. Many of the old trades and skills have also changed and boundaries between well-known trades have broken down. Finally, not to be forgotten, completely new requirements as to public activity are now popping up.

I should like to talk for a moment about standardization. Until recently, standardization was used to bring order to a field that had grown out of hand or it was the standardization of desirable, foreseeable, future trends. The standardization we are referring to now will carry out our modular building projects. For these projects we need components on the market, and we need something to govern the design and manufacture of such components. Therefore, we have had to start the whole thing by making up new standards. By far the most important among these are the various dimensional standards.

This brings me to the first very important tool we have in the industrialized building process, "dimensional coordination." It can be explained in many different ways. I am a little bit astonished, being a Dane, that it has not been a greater success in the United Stated where the whole thing really started about 40 years ago.

The introduction of a common measurement was the beginning. Over the ages we have had several things, inches, feet, the brick, as the basic unit of measurement. But, now it was finally proposed that all over the world there be one common basic unit of measurement. The advantage most often mentioned of having one unit of measurement, dimensional coordination, is that we can avoid cutting sheets, pipes, etc., so there won't be so much waste on the building site. In connection with dimensional cordination, it is necessary to take the broad view and not forget any of the many advantages it can provide. To take a broad view brings you to the problem of preferred sizes. It is generally acknowledged that if you have a functional component of some kind you want it to become modular, you have to amend the dimension at least a little bit. This costs money.

At this point, some people will say that this makes modular building too expensive. But, if we take the broad view, is this really so? For example, in an office building, the total expenditure over the lifetime. of the building, would be about 92 percent for salaries, 6 percent for services and maintenance, and only 2 percent for initial building costs. Of the initial building cost, the major part can easily be services. So, if

we talk about amending the sizes for the structural components of the building, we are really only talking about adding a little bit to a fraction of the total cost for this building over its whole lifetime.

As a result of the broader view, we have developed a Danish standard recommendation containing a series of preferred dimensions. These preferred dimensions have certain advantages mathematically. This new standard has meant a lot. Quite simply, it has provided us with two things: Preferred dimensions which make production and manufacturing more economical for the producers; and at the same time, preferred dimensions which have the characteristic of being able to be divided in more ways than most other figures and dimensions that could have been selected. This means that the practicing engineer or architect will have a much higher degree of creative freedom than he would have had with other preferred dimensions.

The result of our approach is that you will find series of prefab modular components both for highand low-rise housing on the Danish market. Many prefab modular components are manufactured based on Danish standards or Danish standards recommendations.

The component approach has given us one more economic advantage. Usually, in what we call the old way, the prefab factory produced a closed system. A big investment was required, and such a factory, even if it could produce everything itself, which it very often did not do, was able to produce only very few house types. By far, not enough to cover the demand.

By using the component approach, we have been able, with a much smaller investment, to produce various dimensionally coordinated components. These components can be put together in many different ways to form many different kinds of housing design.

How can anyone find out how to detail or to design a modular component? For the first big modular project we had in Denmark, project design and component design went hand-in-hand. But, when the first projects were over, modular component production went on and manufacturing of new types of components was also started. The designers and manufac turers had to program the field of applicability for the components. This subject of definition of the field of applicability is most important. If the field of applicability is defined in a very limited way, the job for them is usually easy, but the market will also be relatively small. On the other hand, things can go to the other extreme.

We can approach this a bit more systematically if we look, for example, at exterior walls and define the field of applicability so narrowly that we say it is enough that these components can be used for a straight exterior wall. Then, the job at hand is easy. but the market will be restricted. On the other hand, it is evident that if we want to be able to use a prefab component in all types of strange assemblies, it will be tough work detailing and manufacturing such a component.

In Denmark, we have found out that the first assembly to be solved is usually two components in

a row. The next is usually the outgoing corner, and the third assembly, the ingoing corner. This seems to be extremely simple, but if you check systems actually on the market, to your astonishment you will find that only comparatively few of them have the third ingoing corner solutions build into the system.

In principle, the wider the field of applicability for a component, the wider the market. But, also, the more work you have to put into developing the component.

We have no special difficulty, in Denmark at least, in pressuring manufacturers to do this work. Working their way through more and more modular details, they develop a commercial interest in doing so. They widen their market with every single detail for which they work.

For component catalog building, we stress the importance of working in what we call the field of application because so much is decided today on the drawing board. In the old days, we could cut into things and we could really create buildings on the building site, but the moment we approach prefab component building for good, we must recognize that the building is completely finished when the design. has left the drawing table. The building will look exactly as imagined by its creator.

Therefore, it is on the drawing board that we decide how future generations are going to live. If we make our components the right way, we will be able later to put them together in a creative way, making building and building environments as meaningful as those in the old days. If we, on the other hand, design components with a too limited field of applicability, they can only be put together in monotonous rows of very simple buildings.

Fortunately, there is no doubt about the trend, more and more will be required from the components. They should be created with wider and wider fields of applicability.

The first tool we had for component building was dimensional coordination; the second tool was the performance concept. I shall not go into this to a great extent since much work is being done here in the United States. I would just briefly mention that we try to get down on paper, not how components should be, but how they should be able to perform. We try to aim as high as possible when we formulate our performance specifications. If we do not have the right policy, the money, or the technology to get the right solutions, then for the time being, we get along with something less. But, we try to aim high and to be able to revise at frequent intervals the day-to-day solutions. In the performance concept a very important thing is the development of new testing methods. This is really the biggest workload and by far the most expensive thing in connection with the development performance requirements and performance specifications.

We need to reevaluate many hundreds of old testing methods which we have relied upon. Quite simply, we must do this because they are not performance based. We need new, performance-based tests. There is only

one more thing that I should like to mention in connection with the performance concept. This is that the whole purpose is to make specifications, or regulations, permit more innovation than before. Therefore, it is really necessary to use fantasy when trying to work out performance specifications. An awful lot of imagination is needed if we want the performance concept to work.

Yet another tool for component building which we had in Denmark was the government initiative. We had the usual vicious circle that no one would break. No one would take the initiative to invest. The Government made up a 4-year plan for all of the 8,000 units and promised industry that over a 4-year period, 2,000 housing units a year would be built using only prefab modular components. The response of the industry to this initiative by the Government was very positive and immediate. A few years later, you could even find statements from the bigger firms that the official initiative had justified establishing new highly mechanized factories.

These were the tools in our striving to obtain component catalog building. Next, I should like to briefly mention a little about the work that must be done. The greatest amount of work to be done involves joints and tolerances. The development and accuracy of joints is really a very big problem. It is a rather complicated problem but one we have to solve for the whole series of components if we are to be able to build in a flexible and valid way. This means that we have to solve the problems of accurate joint detailing, and so on for all the types of joints found in components.

As an example of how wrong the whole thing can turn out, in one case, prefab brick components with a backing of lightweight concrete were manufactured to a very high degree of accuracy. The manufacturer, however, had not yet learned how to put such components together with adjustable bolts. He just put them on in the way he had always put up bricks and the result was completely impossible. In only 4 months time, the firm went bankrupt.

Some good work is also being done. Big concrete components, with the weight of 2 to 3 tons, are being manufactured to tolerances of plus or minus 3 millimeters and dimensions of from 2 to 5 yards. To control accuracy, some quite expensive machinery has been built. For instance, floor slab components about 40 M long and 27 M wide, with 2 M thickness are being measured with electronic feelers. By using this method, we can control linear measurements and form tolerances as well. I mention this because the whole thing, dimensional coordination and component building, would be to no avail if we could not control the tolerances.

We have to some extent reached the point where we can say we have catalog component building in Denmark. It is quite common at any one project in Copenhagen, for example, to find big components with name shields from firms all over Denmark. Denmark also receives components (prefab reinforcement and things like that) from its neighboring countries.

Earlier, I treated standardization and said a little about definition of the field of applicability of components, but there is still a missing link. We need a way to get the information from the component manufacturer to the practicing engineer or architect. This being the case the literature (the catalog) gains in importance.

If properly presented, the information contained in the trade catalog can be used several times during the design phase of an ordinary project. First, the information can be used when modular details are sketched. Secondly, the catalog can be used to check whether the components we need are available on the market, and finally, if it is a really good catalog, we can find all of the necessary working details. Thus, the prac ticing engineer and the architect can be spared an awful lot of work.

In Denmark, we have tried to create some standards for presenting the information about prefab modular components. I think we have succeeded in persuading the manufacturers that it is worthwhile to follow our recommendations.

In connection with approval of new components, it is required that information be presented in exactly the same way. This takes the form of description text, drawings, and details. The recommended way of presenting things is exactly what the practicing engineers and architects need.

So, if the manufacturer will follow our standard directions, he will save quite a lot of work for himself and can use the same presentation several times. Some manufacturers have followed our instruction to such an extent that they make a joke out of it, showing far too many different ways a certain component can be used. Other manufacturers take it more seriously, showing the field of applicability, various uses and solutions and all necessary details.

We have even organized this catalog business and have a building center which centrally edits data sheets and certifies that the components shown have been officially approved as being modular. In the case of windows, as an example, data will contain a photograph, the necessary text, the details and the modular

sizes in which you can get the window. On the reverse side of the sheet, you are given the field of applicability and the various window holes into which the standard modular window will fit. The manufacturer has even proved through details that he can provide suitable joints for the solutions he says he can handle. As a last step in the direction of catalog component building, we have taken up work with systems and components that have a very high degree of rationalization. We believe that in a very short time, enough standard multisystem components should be available to cover the whole market in Denmark. However, we are not only concerned with systems and the big components. We also have smaller traditional components like modular blocks in the catalog. In this case, a new modular block was developed. The result is that we can combine traditional and component catalog building. We can erect a modular, rather traditional, block structure and clad it with prefab modular components.

The reason we are very much interested in these more traditional things, is quite simply the economy of the whole thing. We have been able to register that where we once used 22 man-hours per square meter in traditional and completely conventional building, as soon as we started to rationalize we cut down to 15 hours per square meter and when we really started to coordinate things, we got down to 13 hours per square meter. Finally, by using the prefab modular component method, we got down to 9 hours per square meter. Presumably, the next step is that we get down to between 4 and 5 hours per square meter. This naturally indicates that we can save a great many working hours, as expected, by using prefab methods. It also shows that the first very important steps which do not require enormous investment, will give us very big advantages. This is the reason that we are also interested in the more humble kinds of rationalization.

In conclusion, true component building could be done 5,600 years ago with stone prefab dimensionally coordinated components, with no mortar in the joints. And, to my mind, there cannot be much doubt that the catalog component building approach is still feasible and the way of the future. Thank you.