The smell of the Black Forest

This week the show has really started. Eight strong Germans have arrived from Oberharmersbach, bringing with them truckloads full of fresh spruce panels and beams from the Black Forest. Assembly is fast and accurate. So far so good.

 

Anticipating climate change

When you design a ventilation system for an office that should last many decades, what assumption do you make for atmospheric CO2 ?

The ventilation system in our new office will be the only source of fresh air for its 50-140 occupants (windows can be opened, but there will be no need to do so). Sizing and designing that ventilation system is critical if you want to make sure the air quality inside is top notch. Research has shown that a CO2 concentration of 800ppm (parts per million) is the maximum value of CO2 to strive for in an office. 


Obviously CO2 is not the only pollutant in the air, but it is much easier to measure than other values and serves as a good indicator of air quality in general. So our ventilation system will measure CO2 levels (plus relative humidity, temperature and pressure) in all rooms and increase and decrease air volume to ensure the concentration stays between 600 and 800ppm. In order to do that it will pull out "dirty" air, send it over a big rotary heat exchanger (which recovers heat and moisture) and replace it with the same quantity of fresh air.

When you decide how big the ventilation system should be to keep CO2 inside below 800ppm, you need to know how much CO2 is in the fresh air outside, or you don't know how much "refreshing" capacity you are installing.

And this is where it gets quite interesting... Nearly all building guidelines prescribe a concentration of 350ppm to be used for atmospheric CO2. Which was the atmospheric CO2 concentration in the 1990's....

But why were we building an ultra sustainable Energy Plus Office again ? Right, because atmospheric CO2 is rising way too fast, causing climate change and threatening the survival of our species on this planet. In fact, in my lifetime it has risen from 320ppm to 400ppm, the highest value in over 800.000 years.

Now, if we assume 350ppm for atmospheric CO2 as prescribed, this means that the outside air has more "refreshing" potential because it can absorb more CO2 from our office before it needs to be replaced. But since atmospheric CO2 has already reached 400ppm, we will in fact need more air volume for the same amount of CO2 absorption. 

If you think about it, all buildings that have been designed based on 350ppm in the last 20 years either have to start accepting higher and higher internal CO2 levels, which is not ideal for health and productivity, or open their windows more, which is very bad for energy efficiency.

So what did we decide? Despite the fact that we hope the world will radically change course over the next few years to limit its CO2 emissions, we want to make sure the office stays healthy and efficient, so we designed our ventilation system for an atmospheric CO2 concentration of 450ppm, which is what is expected in about 20 years from now in the "business as usual" scenario.

I sure hope that in 20 years time we can look back and conclude that the human species was clever enough to avert disaster by switching quickly from coal, oil and gas to renewable fuels and by stopping deforestation. The technology is already available and the economy will be much better off.

In that case we can then all be very happy that we oversized our ventilation system and that we will never need to run it at full capacity:-)

Smart Construction : Common Sense

During the preparations for our new office we have not only tried to be smart in the final design but also smart in how we were going to build it.

A few years ago, when we built our zero-energy-home I noticed how much time, materials, energy and money are wasted in the traditional construction process. Anytime you build a one-off design, using project specific details and materials, assembled by a team of people that have never worked together before and who are supposed to deliver top quality while working outside in wind and rain, you can expect some problems. 

In our own business, when we build machines, we do not make money on the first unit of a new design and usually not even on the second and third. And that is despite our best efforts to avoid problems in the design and to find them during prototyping. We only start making money once we have ironed out all design problems, replaced some components and fine-tuned our purchasing and manufacturing process. By contrast in the construction busines many companies never get a chance to apply the lessons learned.

EXPERIENCE COUNTS

So, for our new office I decided that some things needed to change. First of all we started the process with the same design group, consisting of Rob Wolfs (architect), Ron Hochstenbach (technical consultant), Jos Wagemans (project manager) and myself. The team was enlarged with Robert de Boergraaf for all consultancy and design work on heating, ventilation etc.

INDUSTRIAL PRODUCTION

Second we set up a program of requirements which included not only the goals "energy-plus-office" and "cradle-to-cradle" but also "industrial production". With this we dictated that we want the construction to be based on a detailed design in 3D and on pre-fabrication of parts in a controlled factory environment, ready for fast assembly on site.

FULL CONTROL

And third, I decided to build without a main contractor. Instead we build under the name of our own company, directly enlisting subcontractors. Jos Wagemans was recruited to project-manage the process on a full-time basis. Having a owner's representative as project manager on site 100% of the time is essential for quality and cost control.

PLANNING

In working with subcontractors we made sure that the boundaries of their work were very clear and that we allowed separate time slots for each to minimise interference. For example, once the concrete basement (below) was ready, the subcontractor cleaned everything up. 

Today they handed the site back over to us for transfer to the massive-wood subcontractor from Germany for the next 8 weeks. The first truck with wooden panels from the Schwarzwald arrived today in time for assembly next week.

Only when the massive wood subcontractor wood is gone will we provide access to subcontractors for roofing, façades and windows. And only when the building is completely closed will we provide access for installation of heating, ducting, cabling, etc. The goal is to make sure that every major subcontractor can do his job without interference from others. Obviously it was essential to take that goal into account when designing and planning the building.

Smart Construction is Common Sense.