We are NOT Keeping up With the Times.
For a number of years now, the building industry has been focusing on improving the insulated value of roofs and opaque areas of the commercial building envelope. R-values of 50 for the roof and R23 for the opaque vertical areas are now common. These are very good values and contribute greatly to energy conservation and the reduction of carbon emissions. However, when we get to the vision areas of the glass, we tend to fall well below what many would consider an insulated area.
Less than 10 years ago, it was acceptable to provide a curtain wall with an assembled U value of 0.40, even in the coldest climates. In its simplest form, this is an R2.5 – not what I would consider a very good insulated product. Today, codes have improved and if you live in a state that has adopted a more stringent thermal requirement, you will have to provide an assembled U of 0.34, or an R2.9!
Unfortunately, minimal improvements like this will not provide the energy savings we need to reduce carbon emissions that will allow us to meet the challenges we all face. If we are to make any real impact, we have to make drastic changes in thermal performance of curtain wall and window designs for the commercial market. U values of 0.20 and below will be required if are to meet the challenges ahead.
I am not recommending the reduction of glass on a building in order to reduce carbon. On the contrary, I am recommending we increase the amount of glass by improving the performance of the curtain wall. It is unfortunate that many of the products used 10 years ago are still in use today. The technology has changed very little with regard to the framing systems – the weakest link of the assembly. The use of gaskets for thermal separation is still common in pressure bar systems and strutted systems are still common in unitized walls. Both are well proven, but they have been in use for decades and have limitations when it comes to thermal and structural performance. Many of the major manufacturers have relied on glass to provide performance and disregarded the framing. Unfortunately, the framing has a larger impact on the performance than many thought and the lack of R & D is evident.
But there have been a few companies that were visionary and have invested heavily into R & D to create framing systems that can provide U values of 0.28 with 1” insulated glass and as low as 0.138 with triple. These values are available today and at a cost that will not break the budget. It is common that when someone hears “high performance”, they also think “high cost”. But these companies put a high value on keeping the costs down, knowing how sensitive budgets are. These same companies are not sitting still. They have preliminary designs that will achieve assembled U values of 0.10 and lower. These will be ready for the market within the next 12 to 16 months. These are the performance values we need to make a difference.
The commercial building industry has not kept pace with the market demands. We all make a commitment to a challenge such as the 2030, but when all the low-hanging fruit is picked and we are left with the real tough choices, we choose the easy road to take. There are a lot of reasons why and we all know what they are. The industry has to do better, and it can. The question is, do they want to?