Building Energy Efficiency in the Tropics Text Version

Below is a text version of the presentation given by Kosol Kiatreungwattana of the National Renewable Energy Laboratory (NREL) at the Low Carbon Communities in the Caribbean Workshop on March 1, 2011. The workshop was held at NREL in Golden, Colorado.

My name is Kosol Kiatreungwattana. Today we're going to — I think you guys have heard about — so many things about information — a lot of information. But now we're going into a lot of details in the building science.

So talk a little bit about the session agenda — we're going to look at an overview of the building energy efficiency, what kinds of strategies would be appropriate for the topics — and the analysis too, and then the references and resources available for you guys. And at the end, we'll open for the questions and answer.

A quick overview on the energy consumption/the energy supply. You guys are probably pretty familiar. We [US] are one of the highest in energy use per capita in the world. And, in general, you can see on the boards, it's a quadrillion BTU — the way that we're spending or supplying on the energy.

And on this side, you can see that the combination, combined with the buildings, is about 41 percent of the energy consumption in the United States. And the building uses about 70 percent of the electricity that's produced in the U.S. So it's really, really important to focus on the efficiency elements of the whole energy reduction/energy independence of the United States.

So we talk about the building design — what kind of strategy are we looking for? A lot of people — when we talk about the renewable energy is like — "Yeah. It's very sexy. It's great." But you guys have to focus on — technically, the energy efficiency is a lot cheaper than the renewable energy. I'm not against it.

Because at the end, we're going to be integrating all the renewable energy into the projects. But we want to make sure that you guys have to maximize the energy efficiency first, and then go with the renewable energy. So for your climate, you want to make sure that — because you guys have the cooling dominant — basically the cooling load dominant. So you want to make sure that you minimize all the cooling loads in your buildings by minimizing the use of air conditioners.

But you want to make sure that you still maintain the comfort. And then at the end, we're integrating the on-site renewable energy. I like to focus — that we're looking for the new construction, the existing building — usually the new construction — you focus, and you're going through the energy codes, which is like — either it's going to be ASHRAE 90.1 International Energy Conservation Codes 2009-20012 or the Tropical Energy Codes.

And right now, there are a lot of studies showing that an optimal design — you can exceed those baselines — those energy codes up to 30 to 50 percents. So with a good design, you can achieve that level of performance. For the existing buildings, a lot of things make it more difficult to achieve in particular on the building envelope, and on the other improvements.

But somehow, you still are asking, "Are we looking for achieving something in the 30 percent or in that range? "At the end, when you're combining, looking at, or integrating this energy efficiencies, you want to make sure everything works correctly, as designed.

So I recommend doing building commissioning at the end including measurement and verification and also either long-term or short-term performance monitoring. Let's start looking into strategies. I'm going to go into a high level. But at the end, if you guys have a detailed question, and you want to go into specifics, we can go into that detail as well.

Well, as we're looking at the siting, when we generate any new construction, we're looking at: what's the location? What kind of environmental impact is going to happen to those buildings? And then what kind of infrastructure you have to look at. Sometimes it's better to — this is a good location.

Everything is about location, transportation. Infrastructure is better than the other side. Orientation? For orientation — for a good design, you want to basically use the orientation to benefit you. Technically, you want to design and orient the building to minimize all the solar heat gains into the building.

However, you also want to maximize the use of the daylight. So it's a balance between: how can you introduce the daylight into the building, without introducing too much of the solar heat gains getting into the building?

Talk about shading. The shading — we have to take into considerations — particularly, again, you want to minimize all this solar heat gains into the shading using exterior shading. For interior shading, you want to make sure you have the windows covers, — window blinds and deploy the overhangs.

And what kind of impact will this have on the building shape? Either it's going to be from the building next door or the trees that might shade the building, which might benefit you, or might not benefit you. I want to share these kinds of preliminary studies. I know that you guys are going to do a tour on our research support facility in the afternoon.

This is a preliminary study, where we're looking at building for what kind of optimal building form we can get to maximize the daylight. So looking at the spacing of the buildings that we don't want to have the building to shade another building. But also to maximize the aspect ratio and the form of the building to get the daylight.

Let's go into the next one, the building envelope. The idea of the building envelope — again, you want to optimize it for the Tropics, sometimes, you guys have a great, great climate. It's either mild or a little bit on the warm side. But you want to make sure that the building envelope benefits you.

There are buildings — even though they are not air conditioned, you might still consider adding or improving the building envelope on the wall, on the roof, by adding the insulation. Make sure to include the vapor barrier, radiant and air barriers, or a cool roof or a green roof, to cut the heat transfer through the roof.

Although some of the space is unconditioned, adding insulation, sometimes, is not necessarily going to save you a lot of energy. But it will improve a lot of comfort for the space. For windows, the U-value might only show a slight improvement on your energy.

Solar heat gain coefficient, you want to make sure, for your climate, your windows have a low solar heat gain coefficient. And the amount and the placement — you want to avoid east/west/south. But sometimes your building will not get daylight.

That means you have to have good sun control in some of the orientations — like the south-facing. Under shade. Make sure you have overhangs, blinds. The next one — we talk about lighting. Lighting —not only gives the space lighting, but also gives you the heat gains.

So you want to make sure that you're going to use as high efficiency lighting as possible, and also the daylight with dimmable controls. Now as you're probably really familiar with all these high-efficiency lighting bulbs such as compact fluorescence, and LED. Also make sure that you're using a motion sensor for spaces where the occupancy varies a lot. So you want to make sure you're using an occupancy sensors, the timers, which will help you.

A lot of new design — you can design the lighting in the space at a lower ambient lighting level. But then you're supplementing by using task lights. You know? It's going to still give enough lighting for people, at a lower ambient light. But for specific tasks, you use a task light. For the plug loads and the domestic hot water looking for the Energy Star products.

For the new Energy Star products, — you will see a lot of products qualify for Energy Star. But the energy rating for each one varies quite a bit too. So make sure that you pick the right one.

Power server mode. For anything that enables you to use a power server mode — such as computers or something that would go into a standby mode, make sure that you set up to turn the vampire power or phantom loads off.

In the past, nobody paid attention to these kind of loads. But you can start hearing more and more about this vampire power or phantom loads. In general, there are some studies that demonstrate that in residential energy consumption, it could be as high as five percents of the energy consumption.

So either using a timer, these days there are smart power strips that detect when the equipment goes into standby mode, it turn itself off. And then it's smart enough to wake it up when you want to use it.

Laptops versus personal computers. Personal computers, these days, are very efficient. But if you compare to the laptop, laptops are more efficient. The price of a laptop also goes down. You can save energy easily — a quarter or even one-third of the energy of the PC.

Data Center. If any of your facilities have a data center consider design and manage a data center, and the HVAC that supplies and conditions those spaces — there are a lot of efficiencies that can go into the data center. This evening, you will tour the research support facility — we have a large, large data center in there. We will be presenting the efficiency for that data center to you later on.

I came from Thailand. The climate is similar to yours. I'm familiar with the way that we're using the domestic hot water. And it could be a big load for the residential.
In Thailand, we use instantaneous electric type. It probably similar to what's over there. Using solar to heat the hot water — either a flat plate or evacuated tube, or as simple as a thermosyphon technology.

One of the technologies that are starting to become more popular is the hybrid hot water heater. The hybrid is between using the heat pumps and the electric resistance system. Basically, you run your base load with a heat pump. And then with any peak, you're using the electrical system to boost up the temperature to meet the peak.

And using the heat pump — technically, it's using a refrigeration system cycle to heat that water. And you can get about three times more efficient than using the electric resistant system. What kind of heat recovery can we use? Consider that sometimes you might be using a lot of hot water, and everything's going out into the drain. Is there any way that you can capture that?

Is there any way that we can use waste heat? Either it's going to come from a process or even from the condensing side of your air conditioner. How about the HVAC? HVAC is definitely the big load for your climate. But make sure that — is there any possibility that you can use natural ventilation?

A good design gets into a good wind direction and uses operable windows. We'll show you on the tour of our research support facilities, where we use a lot of natural ventilation during summer, and also during spring.

A ceiling fan. Is there a way you can use it instead of the AC, or by setting your AC a little bit warmer, but then use the ceiling fan to circulate the air in the homes to improve the comfort? A whole house fan is also a good option to use for specific time — like in the morning or in the evening.

It works really well at any temperature difference, like five degrees Fahrenheit. So any time that your house starts getting warmer than the outside by over five degrees, you may use a whole house fan. But you want to make sure it's not 100 percent humidity outside. You don't want to do that. But you have to pick the right time. High efficiency air conditioners — the energy codes require any home to have a SEER (Seasonal Energy Efficiency Rating) of about 13 right now. But the best that you can buy in the market is about SEER 21 or 22 these days. And we highly recommend SEER 14 to 18.

There are some studies in Hawaii which has similar climate to yours. I will show you the results later on. Because the humidity is like the big enemy for your climate, so is there any way we can do evaporative cooling, use the indirect evaporative cooling.

Make sure that a programmable thermostat is integrated into your AC. A programmable thermostat is inexpensive. It's a no-brainer. Everybody should use it.

And there might be some sophisticated controls with some ACs, which will allow you to, during the night — instead of staying very cold, like 72 to 74 degrees all night — there might be some control that increases the temperature at every hour, one degree warmer each hour at night. You won't even feel the difference.

Demand-controlled ventilation. We want to make sure that the building is still healthy with proper ventilation air. But you want to make sure that it's appropriate — not too much. The demand-controlled ventilation is a good strategy. Energy recovery. For any air that you bring into your building — it's going to be any air that you have to exhaust or vent it out as well. Is there any way that we can capture the cool air that you have to vent out?

Using premium efficiency motors with variable frequency drives. Any motors — is there any way that we can control the motors better, where they don't have to run at a constant speed all the time? For the variable air volumes system, —the modern air conditioning systems are moving towards a dedicated outside air system because they want to make sure that the outside air they're bringing into the building — is precise. It's optimal. And then it's easy to control moisture and all the dehumidification that you have to do. You don't have to do at the main air system but you're doing it at the dedicated outside air.

At the end, you maximize and optimize your energy efficiency. Then you want to go beyond. You may want to integrate renewable energy such as solar photovoltaics, the wind power, the small hydro, the biomass, and the geothermal.

When we're looking at energy efficiency, there are so many options. How can we evaluate? Everything is interactive to other systems — building envelope, heating system, cooling system, and lighting system. It's all interacting. So you want to make sure that you're using a whole building approach when you're doing analysis — to make sure that you capture all the interactions among the systems.

When you're doing analysis, set up the performance target at the beginning, and gauge the whole idea of energy efficiency at the earliest point of the whole design. The performance target either is going to be — "Oh, I'm looking at a LEED rating — a U.S. Green Building Council high-performance building. You're either going to go with LEED Silver minimum — or going gold level. Or just the energy efficiency itself such as, "I'm looking for 30 percent or more aggressive like 50 percent better than energy codes."

The way that we're going to evaluate all these energy efficiency strategies this is what if analysis — it's a lot cheaper, if you're doing anything, if you learn about your building by creating an energy simulation program and doing "what if." "If I'm going to do this, how much I am going to save" What kind of investment is it going to be? What kind of impact will there be to the other systems?"

What the role is building energy analysis? You want to make sure that you integrate everything as early in the design as possible, even going to a pre-design. And you can see the way that energy analysis interacts into each of the processes.

Talk a little bit about the tools that we have. Energy analysis tool is the residential building. It's called BEopt. This is a front-end, using a DOE-2 and TRNSYS to run the simulation. But it's an optimization that we select a list of energy efficiencies that we want to analyze, and then use the software to find out the maximum savings at the minimum cost that you can get.

In the traditional way, you would do like this "Okay, I have 10. I'm going to run 1 to 10, 1 matching with 2, 1 with 3. How about 1, 2, 3?" But with this software, we're going to run everything, and then select the optimal options for you. I will talk about the concept, a little bit, on the algorithm behind the scenes.

You're starting with the building — these are your utility bills. You might be able to do some energy efficiency improvements without adding any cost. However, you start implementing something more, and you start investing your capital costs.

I'm paying through my mortgage or some financing. Your energy costs or your utility bills start going down, but you start paying some investment in there. And then you will max out at some optimal design that you can get. And here is my investment.

However, going a little bit further, it's going to cost you a lot more. There might be some improvement that's pretty crazy expensive. I'll just give you an example. I'm going to rip up the whole wall. I'm going to add insulation, put in a new roof or whatnot. And then it's costing you so much. Maybe we should consider renewable energy, when the costs of efficiency measures start getting too high.

At this point, we start integrating and adding renewable energy. In this, for example, we're adding a solar photovoltaic system, and then going, going, keep going. This is a net zero energy path. You're going with the efficiency as much you can get. And then supplementing with the photovoltaic system, you get a net zero energy building.

 

I'll give you an example. We used this analysis for the State of Hawaii. We used the 2006 International Energy Conservation Code as a baseline. This is the utility rate and the market rate, and then the cost of the PV system. In this analysis, it's showing that the net zero energy is cost-effective, and it's possible.

I'll show you the results at the end. Because it's going to summarize everything. This is the energy efficiency package we recommended.

The air conditioning unit — it's a conditioned space. You're going with the minimum cost. Well, you have to go with the SEER 17 — if you're going to net zero, you're going to SEER 18, seven kilowatts of the PV system and so on. So we can look at: what are the options for you with the AC and without the AC? We use the SEER 13 as the baseline.

This is another example that we did for St. Croix's affordable housing. Very similar. And we explored these options. And for this study, we were not looking at any PV options. We want to look at what kind of optimal efficiency package we can get. So these are the results — very similar to Hawaii, in the way that we do it with AC and without AC, and what kind of optimal package we recommend.

What kind of tool are we using for commercial buildings? It's a very similar concept. But the tool is called OPT-E-PLUS. This is the building energy optimization tool for the commercial buildings. We're using Energy Plus as the simulation engine, and we're doing life cycle cost analysis on that too.

I want to point out that for the Energy Plus models, there are already built, already available — for any analyst who wants to use it. It's called the DOE Commercial Building Reference. There are16 prototypes, and for 16 climate zones. I will show you, also at the end, what details that you can get into this model.

Open Studio is a front-end tool to create the geometry of the building. It's a lot easier to draw with Google SketchUp — a front-end that you can use to draw the 3D model. It's pretty easy.

Again, this afternoon, we're giving you a tour of our research support facilities. You can see this is the LEED Platinum, and the larger net zero energy building this is a Class A commercial building. And something interesting about this building — this is all energy efficient. There are many great, great energy features integrated into this building.

But one piece of interesting information about it is the cost of the building. The cost of the building has turned out — even in a high-performance building like this, the cost is about $260.00 per square foot, which is about the same or comparable to any Class A building in the whole United States. So the idea is we want to prove to you that a high-performance building is not necessarily a lot more expensive if you design it well.

(Interruption)

I'd like to go over a little bit about the resource information. You asked — Green Building LEED Rating — it's a very good resource. Whole Building Design Guide is also a very good resource for you. ASHRAE Advanced Energy Design Guides. There are already studies for these types of buildings for 16 climate zones.

And for your information, all these analyses are also using OPT-E-PLUS to do the analysis. This is also a very good example of information Solar Decathlon is the national competition for a solar home from 20 universities in the United States competing.

These are three good examples. These homes are designed for a hot and humid climate. And on this website, also, you can find all the information on the project manual, the design, architectural drawings, mechanical, electrical, plumbing, and construction cost information.

Other resources — Building America creates a lot of buildings analyses — the best practices for hot and humid climates. Also, case studies, affordable housing. These are very good resources for you to check out.

Thank you very much. Any questions?