Hi HVAC Efficiency: 3 Part Series: Part 1: Innovations Offer Reductions In HVAC Energy Consumption But Are Often Ignored.

Hi HVAC Efficiency: 3 Part Series: Part 1: Innovations Offer Reductions In HVAC Energy Consumption But Are Often Ignored.

In recent years, the industry has devoted a great deal of effort to reducing the amount of energy used to operate buildings. During that time, a variety of innovative HVAC technologies and design strategies have been developed and proved in a wide range of projects. Those approaches, however, are often ignored when HVAC options are being weighed. That's unfortunate: Wider use of those HVAC strategies represents a substantial opportunity to cut energy consumption, since more than one third of the energy used in a building is for heating, cooling, and ventilation.

Those strategies are also crucial for projects aiming to achieve net-zero energy use. A net-zero energy (NZE) building is one where the total energy consumed over a period of one year, minus renewable energy generated on-site, is equal to or less than zero.

Designing a very efficient HVAC system, whether it's for a net-zero building or not, can be a significant task, and it is best accomplished through an integrated, holistic design approach. This approach requires the commitment and contribution of owners, architects, engineers, contractors, and other specialists. Building owners and facility managers play an integral part even beyond the design stage: Even the best-designed projects rely on the user's motivation to operate the building with a high level of energy efficiency — especially when striving for net-zero energy.

The appropriate selection of HVAC systems offers many opportunities to achieve great efficiency. But the first step in designing an efficient HVAC system, regardless of whether the project's goal is to achieve net-zero energy use, is to cut the demand for energy. This is accomplished by reducing building internal loads, by improving building envelope performance to reduce solar heat gains and conductive losses, and, at the same time, by maximizing the use of daylight.

Depending on the climate, cooling demand can be reduced by increasing building insulation and installing high-performance glass. Light-colored, reflective surfaces on roofs and walls and radiant barriers within ceilings are also important to avert solar radiation.

In recent years, there have been developments in dynamic building envelope technology that can alter performance in order to withstand peak periods. Smart glass or self-tinting products are controlled based on an electric signal. Phase-change materials can be installed in drywall in order to maintain surface temperatures during extended hot periods.

Internal electrical loads for lighting and power systems should also be reduced as much as possible to increase efficiency. About 39 percent of building energy use goes to lighting and office equipment. Reducing internal electrical loads also cuts the demand for cooling: For each kW consumed, a percentage of waste heat must be cooled.

PART 2: Consider These Passive Or 

Energy-Efficient Active HVAC Systems:

Once heat gain is reduced, passive HVAC systems or more energy-efficient active systems can be installed to satisfy occupant comfort.

Passive systems are effective in net-zero buildings because they allow the user to maintain comfort in a space without the need for energy. Common passive techniques include natural ventilation and the use of thermal mass.

Natural ventilation relies on outdoor air and appropriate high/low window placement to ventilate, bring in fresh air, and relieve hot air. Exposed thermal mass can often be provided in the form of concrete, water, or other materials to evenly regulate surface temperatures, even when exposed to heat. Exposed thermal mass is often used in conjunction with natural ventilation in order to pre-cool surfaces at night and store this coolth for daytime use.

Passive systems have two limitations: They can be slow to respond to changes in load, and they can have limited capacity. This makes the load-reduction strategies even more important. In mixed-mode buildings, passive systems are supplemented by active HVAC systems to operate during periods when outdoor temperatures are high or low.

Energy-Efficient Active Systems:

When it comes to active-system design strategies, it's important to remember that any measures that can help occupants maintain comfort without turning on building HVAC systems should be considered. Local personal workstation cooling systems or high-volume, low-velocity ceiling fans may allow facility staff to increase building temperature set-points while maintaining comfort. The premise of "adaptive comfort" is that people can accept a wider range of temperature if they have the means to make adaptive, local adjustments such as altering air velocity, modifying clothing levels, or changing the activity schedule.

For heating applications on small- to mid-sized commercial net-zero projects, electric heat pumps are often the preferred means for generating heat. The reason is that they can take advantage of electricity from on site renewable sources (e.g., from photovoltaics or wind turbines); that's why net-zero projects use natural gas heating systems less often than other types of projects. Other sources of heat, such as solar thermal collectors, are common ways to offset the electrical heating requirements.

Radiant systems, such as chilled or heated floors and ceilings, are effective for net-zero applications both in heating and cooling. These systems temper the environment without needing a fan to circulate air. Air-plus-water systems, such as active chilled beams, can also offset fan energy. A pump is required to circulate water; however, water is a much more efficient medium for transferring heat or cold than air.

For applications requiring large quantities of air, either due to ventilation or cooling demand, a means to offset fan energy should be considered.

The conventional method for doing this is to reduce supply air volume during temperate periods using a variable air volume (VAV) system. A VAV system uses a variable frequency drive in conjunction with the fan to modulate speed. Because fan power depends on airflow and static pressure, some systems look to save energy by reducing static pressure. An underfloor air distribution (UFAD) system can accomplish this goal by moving low-velocity air through a raised floor cavity to reduce the length of high-velocity air ducts. A UFAD system also supplies air at a higher temperature than VAV systems and often uses outside air to provide free cooling, leading to greater efficiency.

For larger applications, central plants employ water-cooled chillers with heat rejection from cooling towers. For this size of net-zero project, efficiency would be the driver for all mechanical components. There are opportunities, however, to use natural energy sources such as geothermal heating/cooling to modulate temperature in the HVAC fluids.

PART 3: Net-Zero Energy Buildings: Waste Heat Recovery And Renewable Energy:

Waste heat recovery and renewable energy are important strategies in net-zero energy buildings.

Because natural gas systems are less often used in net-zero buildings, there are fewer opportunities to recover energy from the heat-intensive processes. If natural gas is not used for heating, a project is unlikely to use fuel cells or micro-turbines, eliminating the ability to recover waste heat from those energy-generating systems.

On many projects, waste heat sources occur within the exhaust air streams or in condenser exhaust from heat pumps or chillers. Depending on the use of the incoming air and the quality of the outgoing air, heat can be transferred using air-to-air heat exchangers, air-handling-unit run-around coils, and thermal energy wheels. These systems either directly or indirectly transfer heat from one air stream to the next.

Another source of waste heat is the exhaust air from heat pumps or condenser water from chillers. If there is a simultaneous demand for heating (possibly in domestic hot water), this waste energy can be reused as a heat source.

Renewable Energy and Building Automation:

The steps outlined are important in another way for projects aiming to achieve net-zero energy use. Those projects decide which renewable power generation system (photovoltaic cells, building-integrated wind turbines, bio-fuel, or some other means) best matches the building demand and profile for the project type and region. Measures that reduce demand also help to reduce first cost of the generation system, and make it easier to deal with the source's intermittent power production. The protocol we've outlined makes it easier to size energy-generating systems at an appropriate and affordable capacity.

Building occupants also play an integral role in efforts to achieve energy efficiency, especially in net-zero buildings. If the user is unaware of the energy consumption in relation to the building energy generation, there is little chance of achieving a neutral energy balance (i.e., net-zero energy use) at the end of the measurement period. Building dashboards allow the user to monitor building energy consumption and to better understand when manual systems should be operated. For instance, the building dashboard may notify the user when outdoor air temperatures are acceptable for opening a window or inform the user when energy conservation may be needed on a cloudy day.

The design of a highly efficient HVAC system, especially for a net-zero project, is a complicated puzzle that requires all members of a project team to engage in the process. More than ever, there is reliance on all members to cooperate, motivate, and inspire their counterparts to achieve the common goal of energy neutrality. The reward is a net-zero building that can meet the needs of the present while having "zero" impact on the ability of future generations to meet their own needs.

Bruce McKinlay, PE, LEED AP, is a principal with Arup in Los Angeles and leads the firm's commercial property market in the Americas. He has collaborated on numerous sustainable projects where an integrated design approach has led to greater energy efficiency. He can be reached by email by clicking the following link here.

Jamey Lyzun, PE, LEED AP, is an associate at Arup and has 14 years of experience on projects. He has applied many of the techniques outlined in this article to assure that integrated strategies at the design phase can lead to low energy and sustainable outcomes during operation. He can be reached by email by clicking the following link here.

Hi A Dark Side of Solar Power!!!

Hi A Dark Side of Solar Power!!!

The harshest criticism for fossil fuels has always been the horrible effect they have on the environment. Not only does retrieving the resource (coal, petroleum, natural gas) do irreparable damage to landscapes and ecosystems, but transporting it can be quite dangerous. And once the fuel has been spent, harmful byproducts clog the atmosphere and have far-reaching effects that scientists have only recently begun to quantify.

You know this, and I know this. And I know that you know that we all know this. This isn't going to be a recital of facts we know, ya know? But what about the negative environmental impacts our cultural shift to renewable energies, namely solar power, produce? There is a side to solar (PV) power that's rarely considered and not well understood.

Energy Payback Time (EPBT):

EPBT is the amount of time it takes a solar panel to collect the same value of energy that was expended in the panel's creation. It used to be that panels virtually never recaptured the amount of energy which was needed to create them, but that belief faded in the 1990s as the technology improved.

A significant amount of energy is spent producing, processing, and purifying materials for PV panels, as well as for the manufacture, transportation, and installation of the panel. The mathematical formula (.pdf) for determining the EPBT looks like this:

Rather than break down figures for areas with my limited text space, I'll just spoil the conclusion: the effectiveness of solar panels is severely affected by material efficiency and the location of the panel. In most of the United States, it takes almost two years before the panels begin to reduce emissions. At what latitude do solar panels stop making sense?

Environmental Waste:

Not surprisingly, China has been the leading manufacturer of PV panels worldwide by nearly fourfold. Despite this robust production rate, they're only second in PV power production (18,400 mW compared to Germany's 36k mW). What gives?

Frankly, China doesn't care about its environment and has little oversight on how companies dispose of industrial waste. And in consideration of the profit the industry is making, what regulations do exist are overlooked. U.S.-based PV panel manufacturers have a hard time disposing of toxic materials used in the production process. Chinese companies don't have the same difficulty, choosing to bury chemicals or flush them in public waterways. The result is a panel which was cheaper to produce and ship abroad.

Really, we're just burying the problem someplace else, hoping that a super-solution from future geniuses materializes in the meantime.

Wildlife Impacts:

The Ivanpah solar plant in utilizes 174,000 heliostats to reflect sunlight onto a centralized solar tower. The tower collects the sunlight, transfers it to heat, and boils water to begin the electricity production process. The plant is located in the Mojave Desert, away from population centers.

Human population centers, at least. While the imagery of a desert solar plant probably conjures images of dust and tumbleweeds, the area where the plant lives is much more lush than you might expect. When the plant was first announced, it incited considerable backlash because it was building on habitat that belonged to the endangered desert tortoise. The plant's construction was ultimately changed to help curtail its effects.

Now that the plant is up and running, an unforeseen consequence has occurred: an excessive number of bird deaths. Birds are lured to the area by insects or migration patterns, but once in the vicinity of the plant they're almost assured a hellish death. Estimates of up to 28,000 bird deaths a year have been attributed to the concentrated solar arrays, which blind and even ignite birds midflight. Officials are considering how to proceed with a megawatt and mega-money facility that may drive the extinction of entire species on its own.

The point isn't that solar power is harming our environment. Without a doubt, nearly any energy harvest strategy will conclude with negative environmental effects. But it shows that a long, long road of development must be traveled before our technology creates the sustainable utopia we envision. For now, we should probably maximize the efficiencies of the energy sources we have.

Hi International Shipping Goes Green:

Hi International Shipping Goes Green:

The world's economy continues to be buoyed by its oceans. Approximately 90 percent of all international trade is exchanged by vessels, and between tankers and intermodal container transport ships, they represent 65 of the 68 largest ships in operation.

Of course, the negative environmental effects of huge shipping vessels are well documented. International Maritime Organization predicts that carbon dioxide emissions from shipping would constitute 72 percent of human-made emissions by the year 2020. Considering cargo weight and transport distance, shipping via sea is the most efficient and economical, but annual increases in the amount of tonnage traded and distances traveled mean most efficiency gains are offset by increased usage.

A variety of engineering solutions have been implemented to keep mega-ships financially afloat.

Wind power returns:

In 2007, German shipping company Beluga Group launched MS Baluga Skysails, a 433 ft. long container ship. Notably, the ship receives auxiliary power from a paraglider attached to the front of the ship that reduces fuel consumption between 20 and 30 percent. The largest of the paragliders, up to 6,500 ft.², can exert as much towing power as a 6,800 hp engine. A pod-based logic controller system links the canopy and the towline to determine the optimal flying height (up to 1,600 ft.), wind direction, and speed.

Overall, Skysails have been slow to catch on, though the company says 40,000 container ships can be retrofitted with the system.

Dual props, slower speeds:

International shipping operator Maersk operates the current largest ships in the world, their Triple E class of container ships, of which there are 20. The handful of vessels larger than their Triple E Class have all been retired and dismantled because they weren't sustainable enough. So when Maersk launched their first Triple E in 2013, they knew that many operational changes were necessary in order to keep the ships viable.

Despite being the largest ships ever, Maersk claims there is a 20 percent improvement in operational efficiency over their second largest fleet of ships, the E class. This savings comes primarily from reduced throttle speeds. Most of Triple E transit is conducted at 19 knots, and the ship have maximum speed of 23 knots. This is considerably slower than other container ships (up to 28 knots), but it is considered the optimum operating speed which reduces power consumption. This adds 2-6 days to each journey.

Efficiency also stems from a unique twin propeller arrangement. Most container ships utilize just a single propeller, as they're more efficient because the dueling draughts of two propellers often result in parasitic drag. But the Triple E class has two 9.8 m four-bladed screw propellers, compared to the single 9.9 m six-bladed screw propellers, contributing 4 percent better efficiency and better pressure distribution. In this instance, the significantly larger disc area of the propellers compensates for conflicting vortices. The ship is also fitted with an innovative, $10 million waste heat recovery system, and Maersk is considering adding exhaust treatment systems as well.

LNG tankers run via boil-off:

While the Triple E is the largest container ship, the Q-max is the largest liquefied natural gas tanker, as it's 80 percent larger than most LNG carriers. Just as LNG trade has increased, LNG carriers have become more prominent. But it would be an oxymoron for a ship that provides for essential services for a booming green industry to also be an emissions giant. As such, the ship uses two low power diesel engines to power a dual propeller arrangement. Since the natural gas needs to be supercooled, the vessel maintains an internal membrane which waffles or compresses to minimize thermal effects on the vessel hull. Naturally, some of the gas transitions to vapor, where a system captures it and returns it to a liquefied state. Most LNG carriers recapture LNG at rates of 99 percent or more.

But the tankers can also run on the boil-off gas from its recapture system. The company that owns the 14 Q-maxs has initiated conversion on its fleet, so the diesel engines can also run via recaptured LNG. The result is a tanker that has a significant reduction in emissions, engines that require less periodic maintenance, fuel supply flexibility, and ultimately risk reduction.

Like many industries, international shipping businesses are adjusting to new environmental regulations that determine in which nations they can do business. Efficiency equals increased profitability, so it's ultimately a business decision to create a new generation of shipping vessels. Until a true bridge-over-the-ocean engineering project comes true, even more efficient ships are needed to offset the increasingly global marketplace.

!!!Hi GREEN DISCLOSURE!!!

Hi Researchers use HIVE to test latest building methods.

Hi Researchers use HIVE to test latest building methods.

A new research facility in Wiltshire is set to 

advance the development of sustainable 

construction materials and systems.

Funded by EPSRC, the £1m HIVE facility will allow construction companies and researchers to conduct realistic, full-scale testing of their facade designs in open-air conditions.

HIVE, located at Bath University’s Building Research Park in Swindon, consists of eight cells that are insulated from one another, each with a single face left exposed to the external environment.

The cells themselves will let researchers analyse the environmental impact of construction materials including their energy efficiency, flood resilience, structural capability and internal air quality.

‘People are interested in looking at the latest iteration of their products and trying to compare them with previous iterations or with competitive products to see whether or not the performance is something to shout about,’ said Dr Mike Lawrence, director of the Building Research Park.

He cautioned, however, that related projects are beset with issues surrounding finding a suitable location to build, gaining planning permission and installing the infrastructure to carry projects out.

Dr Lawrence said: ‘[HIVE is] plug-and-play…we’ve already got the data loggers, all the infrastructure, weather stations, communications [etc.].

‘They can, on day one, start their programme, which saves between six months to a year of time.

‘At the other end when you’ve finished your programme, you often have to deconstruct your building and put everything back to where it started. Again, we’ve got processes where the whole thing can happen much more quickly and effectively.’

Sixteen platforms will be available alongside HIVE for researchers to construct pods of up to 125m³ enabling flexible testing of construction systems and performance.

‘We can whack [buildings] up very quickly because the foundations are already there and when the experiment’s finished take it down and put something else up straight away – all of the infrastructure is there,’ said Dr Lawrence.

Carbon footprint:

The construction industry is widely acknowledged as having a considerable carbon footprint, a situation that Dr Lawrence is keen to redress.

‘The construction industry is responsible for half of global emissions, that’s an enormous amount and big target to hit,’ he said. ‘Let’s try and hit it, let’s both improve its on-going performance but also…make a building with a lower carbon footprint actually embedded into it.

‘So instead of putting in lots of steel and concrete, let’s put in materials which have much lower environmental impact, or indeed where the energy input into building [a structure] is less than the energy stored within the fabric of that building if you convert it into carbon dioxide.’

 Inside the HIVE:

• a hygrothermal cell to evaluate movement of heat and moisture through buildings, energy efficiency, air tightness and acoustic efficiency;
• a double-height and width cell that can be used for flexible construction design, testing façades, internal walls and floors, together with a strong roof, allowing for load testing;
• a flood cell that can be used for testing the resistance of construction materials to high water levels or for testing technologies that resolve the effects of flood damage;
• a bladder cell that enables the testing of construction panels against horizontal loading such as wind load and geotechnical forces.

Hi' Tips to Improve Indoor Air Quality;

Hi' Tips to Improve Indoor Air Quality;

Indoor air pollution is considered as one of the top environmental risks to public health worldwide due to increasing number of building-related illnesses. 

Studies have found that concentration of indoor pollutants is significantly higher indoors than they are in outdoor environment, which is two to five times and sometimes hundred times higher than outdoor levels. 

As most of the people spend 80% to 90% of their lives indoor, indoor air quality has significant implication on sustainability.

Decreased indoor air quality can affect quality of life of the building occupant, increase health risks and increase the liability for building owner, decrease the productivity of occupants and reduce the resale value of the building. Poor indoor air quality can cause “sick building syndrome”, which is a medical condition linked to poor health and absenteeism.

Poor indoor air quality is due to many factors including but not limited to improper building design, inadequate ventilation, off-gassing of volatile organic compounds (VOCs) from furniture, carpets, paints and coatings, cleaning products, and from human respiration. Airborne particles such as lints, dust, dust mites, mold, bacteria, pollen and animal dander also contribute to poor indoor air quality. Indicators that are used to measure the indoor air quality include total particulate matter, total volatile organic compounds (TVOCs), formaldehyde, carbon dioxide (CO₂), carbon monoxide (CO), ozone (O₃), air temperature, relative humidity (RH). Concentration of CO₂ in the indoor environment indicates whether ventilation is sufficient or not.

In the Middle East region, most of the people live in enclosed air-conditioned indoor environments. With rapidly growing population, increase in number of vehicles on the road, high temperature level, ever increasing construction activities, regular sandstorm, concentration of air contaminants in the region is among the highest worldwide. Indoor environment also reflects outdoor air quality and pollution. Transport of outdoor contaminants to the indoor environment can result in occupant exposure to outdoor pollutants that have serious health impacts. In addition, there are many sources of indoor pollutants present in building materials, cleaning products, indoor mold and legionella growth, and emission from interior furnishings, finishing and equipments.

Tips to Improve Indoor Air Quality;

Indoor air quality is influenced by concentration of outdoor air pollutants as well as indoor source of pollution, characteristic of building and habits of occupants. Appropriate building design and mechanical system and control strategies as well as changing occupant behaviour can improve indoor air quality and health and comfort, performance and productivity of building occupants. There are a host of strategies to improve the indoor air quality.

Appropriate design;

Building envelop, orientation, and location of air intake, location of mechanical ventilation systems can contribute to indoor air quality. Hence, these factors should be considered during the design stage of projects to control the main source of pollutants for the whole building.

Whole house mechanical ventilation;

Properly designed and sized ventilation system can supply adequate outdoor air to indoor. In most of the green building rating systems, industry standards such as ASHRAE Standard 62 or Ventilation for Acceptable Indoor Air Quality are commonly followed.

Mixed mode ventilation:

Use of combination of mechanical and natural ventilation systems in buildings, such as automated window controlling systems and operable windows, can help in maintaining healthy indoor air quality.

Air quality management during construction:

During the construction phase, molds can develop due to exposure of building materials with moisture. Dust and particulates can easily accumulate on building materials if they are not protected. The air quality during the construction period can be protected by protecting the building materials from dust and particles and moistures.

High efficiency air filters: 

Filters prevent transports of outdoor VOCs, dusts, particulates and ozone indoors. Use of good particle filter such as high MERV rated filters in ventilation equipment are found to be the most effective filters in filtering outdoor dust and particulates out.

Maintenance schedule for HVAC filters:

Dirty filter can cause sensory irritation. Hence, appropriate maintenance schedule can prevent this to happen.

Use of low emitting materials: 

Use of materials that have low VOC content for products such as indoor carpets, rubber flooring, sub-floor materials, ceramics and ties, plasterboards, or other sealants and adhesives.  Also internal construction materials with low formaldehyde content can be helpful.

Conduct building flush out: 

Flushing out of indoor contaminants thoroughly in buildings before occupancy will help replacing dirty indoor air with fresh outdoor air.

Green cleaning program:

Select cleaning materials that are made of low emitting materials and employ a green cleaning program to reduce contaminant exposure.

Carbon dioxide monitors: Install CO₂ monitors in ventilation system and integrate them to regulate the supply of fresh air according to the building occupants demand. By doing so, if the CO₂ concentration increases beyond a set point, then the airflow automatically increases. 

Sustainable Cities.