Helen Sanders, vice president of technical business development for SAGE Electrochromics, and Stephen Selkowitz, group leader for the Windows and Envelope Materials Group of the Building Technologies Department at Lawrence Berkeley National Lab, had their say on energy efficiency advanced glazing and net zero goal at the WDMA conference.
During the recent Window and Door Manufacturers Association’s (WDMA) Technical Conference, Helen Sanders, vice president of technical business development for SAGE Electrochromics, and Stephen Selkowitz, group leader for the Windows and Envelope Materials Group of the Building Technologies Department at Lawrence Berkeley National Lab, both spoke about energy efficiency, daylighting and the goal of reaching net zero buildings using advanced glazing systems.
During the session entitled “Say No to Small Windows,” Sanders said that the idea of many consumers is that energy-efficient buildings have no windows, adding that in order to increase the energy efficiency of buildings, designers should implement daylighting methods to increase the admittance of natural light. In combination with automated controls, this can greatly reduce the amount of electric lighting being used.
Data from glass suppliers such as AGC, Guardian, Pilkington, PPG and SAGE, as well as lighting control suppliers Wattstopper and Lutron, provide evidence to support that with the correct solar heat gain coefficient (SHGC) and visible light transmittance (VLT), along with glazing technologies and window-to-wall ratio, annual energy capital per building can increase greatly.
“Using natural daylight and dimming lighting controls is actually beneficial,” Sanders said.
Options include integrated façades such as lighting controls, energy-efficient fenestration and light-redirecting strategies, and insulating dynamic façades such as low-E, dynamic low-E and triple-pane low-E, as well as highly insulating dynamic units, resulting in different levels of energy-saving measurements.
According to Sanders, based on the collected data, there is a 20% difference in energy usage with daylighting controls, as well as evidence to support the concept that 40% is better than 30% in regards to window-to-wall ratios.
Discussion issues regarding building codes and standards include factors such as window-to-wall ratio reduction, VLT and SHGC ratios, climate zone obstructions, shading and orientation, but, Sanders said, the key concept to take away is that the “use of automatic lighting controls has a much greater impact than reducing window-to-wall ratio or glass choice and buildings with no windows have worse energy performance.”
In his session entitled “Windows for the Next 30 Years”, Stephen Selkowitz discussed the future of glazing systems and energy efficiency.
According to Selkowitz, buildings are the biggest end user of energy in the US, with about 40%, while 71% of that usage is electricity and 54% is natural gas.
“It’d be nice if there was something you could do to solve the energy usage,” Selkowitz said, adding that glass and windows have a big impact on energy use. In the US, in terms of climate change, energy and carbon emissions, the current reaction is made up of the proactive, stagnant and deniers.
Selkowitz, however, pointed out that in the last 10 years the US has delved into green issues and carbon usage, and there recently seems to be a shift in usage. Based on a comparison of what it costs to save carbon versus energy sectors, production distribution and use, he said, “if you are efficient it pays back – If we lived in an economically rational world this question wouldn’t exist.”
“We’ve reduced the rate of growth but to meet the various 2030-2050 energy and carbon goals we need dramatic reductions never before achieved,” Selkowitz said.
Diverse goals have been set by companies, federal mandates, codes and other standards, he said, resulting in a “threat or opportunity.”
According to Selkowitz, in terms of factors affecting US energy business and policies, there is a severe downturn in new construction markets. With regards to policy on carbon, future energy costs trends are unclear; technologies are reaching an inflection point that shifts from components to a focus in integrated systems; there have been updates to mandatory codes and standards such as new state federal energy savings requirements; and there are new performance disclosure requirements.
Selkowitz said, speaking about façades and daylighting, that there should be a vision to change glazing systems from net loss to net supply, given the successes in US markets. He specifically pointed to positives such as that 2003 showed typical units being 95% double-glazed, 50% had low-E coatings and there was a 30 to 65% increase in energy savings compared to 1973. He suggested that by 2030 future glazing systems should work to reach zero net energy use.
“The idea behind sensible building is to reduce energy as economically as possible,” Selkowitz said. “This concept is possible and the question is, can you do this on a large scale?” He says yes.
If the US sets long-term goals of new cost-effective enhanced product options, and if short-term goals increase savings with better use of existing product lines or tweaks to existing products, zero net energy use becomes a more realistic goal.
Reaching net zero, according to Selkowitz, can be done in two ways: increasing the rate of adoption of existing or emerging technologies such as utilizing low-E glazing everywhere, and developing new technological options.
There are four big areas regarding the steps to be taken, which include highly insulating systems, dynamic glazing for solar control, daylighting and air flow. Advanced glazing systems could even become net energy producers, Selkowitz said.
“If you use the right windows, you get happy people and more efficient buildings,” Selkowitz said. “If you step back and look at how things move, we tend to overestimate the speed at which we move but underestimate the impact we’ve made.”