Paul Torcellini is a principal engineer with the National Renewable Energy Laboratory. As part of the Hanley Wood Sustainability Council for 2014, he will co-lead the Vision 2020 initiative in Energy Efficiency + Building Science.
There are so many ways to tackle energy efficiency. How do you decide what is the best approach for each project, and how do you decide how far you can push a project in terms of its efficiency?
The efficiency of equipment has gone way up in the last couple of decades, to the point that we’re reaching the thermodynamic limit of what we can really do with some of the technologies. You can’t make air conditioners that much more efficient without adding more material. If you think about insulating a wall cavity, you can only capture so much air in a standard 6-inch wall. If you want to talk about increasing efficiency in the wall, you have to then think about a bigger wall or be radically different and talk about things like vacuum insulation. With windows, low-E films have really helped performance, but the next big step would be how to get more glass in there, and that increases cost and weight.
So we look at integrated design. Am I designing the building to be responsive to its climate? It’s about indigenous architecture. The Southwest has heavy-mass, adobe buildings that deal well with daily temperature swings while in the Southeast we traditionally use overhangs to block sun from coming in. Factories in the Northeast have long, narrow floor plates with big windows to bring in daylight. In many ways, when we got electric light—and especially air conditioning—we forgot about those things. How do you bring those pieces back into building design and add the layer of sophistication that computer modeling has today?
With that in mind, how do you design the user experiences in the computer model to help you make decisions? On the computer modeling side, we have found that you can get a 50 percent energy savings by making the right design moves and using the technology we have today. It means strategically putting windows in the best place to bring in daylight and offset electric lighting, but it may also mean not putting in windows everywhere. If the people of the building want to override the system and turn on the lights, it means the daylighting design has not provided a superior alternative.
What’s missing: education, tools, or both?
There’s an education component. People need to know that they can do better. Maybe you shouldn’t have an all-glass façade or big, west-facing windows because the occupants end up putting up shades to block the sun. We have this problem in Denver because the view to the West is the mountains and designers put in a lot of glass. But if you look at a lot of buildings, the occupants have covered up the windows because of the heat in the afternoon. Designers should think about all their options and the long-term impacts of their design decisions.
Another education element is that you need to put tools in front of people to help them make decisions such as whether to put something in recycling or the trash. Unless you label the bins with signs saying you can put this and that in recycling, people often won’t know what they should or shouldn’t put in that container.
How do you encourage appropriate behavior? Engage them. Going back to a daylighting example, we have found that motion sensors are a real problem. The problem is that they remove the occupants from the responsibility of dealing with the lights. You’ll hear stories of people having to flap their arms to activate a sensor or sensors not picking people up. Most motion sensors pick up gross motion, but that backfires. I heard a story last week about a building where security patrolled the space every hour and because of the timing of the sensors, the lights were on all night long.
One option is to better the technology, which means more money. There are technologies out now that can use webcams to determine if you’re in a space, not only picking up whether you’re there but also identifying who you are.
However, in our new office building, if you want to use the lights, you must go find a switch. It connects people with the lights so that they know where the light switch is and may actually hit it on the way out. If they forget, a sensor or sweep control turns off the lights, but this engages people in the process of saving energy.
What are some of the biggest lessons that you learned from working on the new NREL building?
Make the tough decisions up front and don’t change your mind. Decide that energy efficiency is so important that you might give up something else in the space. List those things in order and don’t change your mind.
Your perspective is interesting in that you were the client for that project, but it is an interesting point for designers and builders, too. How can they better help people in creating these lists?
Hire someone else to help facilitate the process. Use references. If you can’t set energy goals yourself or don’t have a full understanding of what they mean, look at what has been done. You can say, “Oh, NREL picked these numbers.” That’s one reason why we do demonstrations.
You can have overlapping goals. If I get to net-zero, for instance, I’m going to get all of the energy points in LEED. A lot of times, things fall into place with overlapping goals as opposed to saying a LEED Platinum building is your only goal. Saying you only want a LEED Platinum building can tap into the movement that simply says, “What’s the cheapest way to do that?” and to be honest, energy gets pushed aside because there are easier elements of LEED.
One of the things I like about saving energy is that it’s a very clear pathway to using fewer resources. But there are still complicated discussions. A lot of people with data centers today are saying they cut their energy consumption by outsourcing all of their IT, sending it to the cloud. But it’s still happening somewhere. Now, in our building, we decided to put in a data center and capture almost all of the waste heat in the wintertime and use it to heat the building. Is that better than outsourcing it? I think it is, but when the boundaries get bigger, they’re harder to think about.
Is it possible for us to get all buildings to net-zero or net-positive?
We did a study six or seven years ago that modeled the typical building stock in the country and asked what would happen if we applied a bunch of energy efficiency strategies such as daylighting, high-efficiency HVAC, and better insulation. We came to the number that we could drop energy consumption in half. So that’s the first step. We would have no problem dropping everything in half if we really made a concerted effort to do it.
When you start talking about zero energy at site, other complications come in. For instance, you only get so much sun on your site at once but for all practical purposes, solar is really the only wide-scale option at the building level right now. Wind on a building has complications from vibration, not to mention that most people don’t like to be where it’s windy enough to have a good resource. That’s why wind farms are remote and we just move the energy to where we need it. I think that’s a good solution but the question arises: Do you count that as zero energy or not? How big is your boundary?
We also studied what would happen if we put solar on 50 percent of each roof’s area because most roofs only get about 50 percent good solar penetration. Some buildings such as warehouses are very clearly net-positive. They have lots of roof area, we barely condition them internally, and if they’re heavily automated they don’t even need lights on. They’re very easy to get to zero. Other buildings, however, are hard, such as high-rise hospitals or buildings more than four or five stories. So you can look at Manhattan and say, “I can’t do this.” But there are all sorts of warehouses in New Jersey that support life in Manhattan. What if you put those together? You could get amazingly close to zero.
So we should be looking at energy on a larger scale than the individual building?
Yes. A community scale is where we usually put it. However, the challenge with that is how much of the elephant can you eat at once? You can say we’re going to make the greater New York area a zero-energy community and everyone will cheer, but it still comes down to individual building owners and individual occupant experiences to make the difference. That’s where the decisions are being made. It goes back to my puzzle of integrating everyone in the process.
What needs to be done to advance energy efficiency on a larger scale between now and 2020?
The number one thing is that people need to know that they can make a huge difference today with the right decisions. Technology helps, but it’s not the only solution. The new LED lights are phenomenal. They don’t flicker and have great color rendering. But, people still have to get rid of the old bulb and put in a new one, and they need to get over the price tag.
We can always improve the technology. A big area of improvement has been controls and part-load performance. I may have a traditional air conditioner with heat exchangers, but I can make each part incrementally more efficient and can tune the speed of the compressor with the speed of the condenser fan to perfectly match my humidity and my temperature so that I’m not cold and clammy. I can tune the system so it works perfectly.
Can you tune the system on a bigger scale? If I have 10 rooftops, is one cooling while another is heating? How do I ramp the buildings down when people aren’t there and ramp them back up when people show up? There is a lot of opportunity and technology there and it is going to improve those types of algorithms.
Do you think the rise of energy benchmarking legislation will raise awareness that certain buildings can perform better?
It certainly brings it to the forefront, but how far so depends on the size of the stick. Not keeping your occupancy permit without a certain energy performance is a pretty big stick that would bring it to people’s attention pretty quickly. Do people care? What is the incentive? If I’ve got a building with a lot of tenants who pay their energy bills, do I care how much energy my building is using? What if the real estate market says my below-average benchmarking means my building is worth less? There are things that need to play out in terms of how people perceive that value.
It’s a step to say people should let others know how much energy they’re using and if nothing else, it gives tenants information that directly affects their bottom line. The question is: Are people more willing to pay more to rent a building that uses half as much energy?
We’ve done a lot of work on the technologies. The next big push is on the people side: engaging decision makers, who I define as anyone that interacts with a building, down to the delivery guy who is deciding whether to prop the door open.
Since 2012, Hanley Wood has conferred with building industry experts to establish a timeline of critical goals and metrics that building professionals must establish and meet by the year 2020 in order to preserve our environment and meet large-scale goals such as those of the 2030 Challenge. Scroll over points in our on-going timeline to learn more about the path ahead in green building. Track our progress all year as the Hanley Wood Sustainability Council shares their perspectives on initiating, tracking, and ensuring progress toward these sustainable priorities and goals. This year's program will culminate in an exclusive Vision 2020 Sustainability Summit in conjunction with Greenbuild in New Orleans, and with a special Fall edition of ECOBUILDING REVIEW.
