SOLAR ABSORPTION CHILLERS

Todays’ generation is faced with huge energy crises, along with increasing temperature as a result of global warming, which can all be associated with the reckless usage of natural resources and waste of fossil fuel. This crises has not only caused the contemporary generation to worry about diminishing resources, but has also resulted in mounting inflation and economy crises throughout the world. I being a Pakistani have witnessed the impact of energy crises that affect each and every Pakistani. The Times identified Pakistan, with highest recorded temperature in Asia, to be one of the 5 hottest countries of the world. With an ever growing demand of cooling system, the country faces a huge electricity crisis. Interestingly, air conditioning of buildings has been identified as one of the major reasons causing ozone depletion and greenhouse effect, reason being the huge discharge of refrigerant harmful gases from the conventional cooling systems. I was therefore quite interested in alternate energy solutions and solar cooling options caught my eye.

For over three decade now, numerous solar cooling techniques have been invented and implemented to facilitate cooling and other needs. Thus to understand and identify the most eco-friendly and suitable sustainable substitute to the currently used mechanical cooling system in Pakistan, I did some research into the available options.  Solar cooling techniques are  classified as open-cycle, closed-cycle and thermo-mechanical. Absorption and adsorption fall under the umbrella of closed-cycle, while open-cycle comprises of desiccant cooling. Absorption cooling based on thermal coefficient of performance (COP) has been referred to as the most useful, cost-effective and productive mode of energy production, as compared to the other techniques. In addition to this, desiccant cooling’s high initial cost, and small power density plus low COP for ejector and adsorption cooling techniques limits their application, making them less favorable as compared to absorption cooling technique.

This lead to a further investigation of the available solar absorption chiller options, in an effort to analyze the best and most suited one for Lahore, a central city of Punjab province, Pakistan. To understand the working of a absorption chiller, I looked at the thermodynamic cycle of a absorption chiller, working of its various parts and ways to compute the COP. A considerate of the working temperature and ways to optimize its working lead to conclude that a flat plate single effect absorption chiller would be the best solution to energy and cooling crises in Pakistan, so as to get the best results.

When deciding for the most appropriate Solar Absorption Chillers (SAC), its following main parts catch attention,

  1. The Solar Collector,

The two factors used to decide upon the solar collector are cost and efficiency. The current research on the subject suggests that expensive evacuated solar collectors should be selected when the temperature required for chiller is high or when the climate of the place is mostly cloudy or has less availability of solar radiation. Even though the comparatively cheaper flat plate collectors are less efficient then their more expensive siblings, evacuated solar collectors, given their smaller payback period and lower deployment costs the former are better suited to areas with less cloud cover and higher solar radiation such as Lahore, Pakistan.

  1. Absorption Chiller.

The Second functional part of SAC are Absorption Chillers. The two main differences between Absorption chillers and Mechanical chillers, the most prevailing type of chillers currently in use in Lahore Pakistan, are firstly, in an absorption cycle heat is used and it is a thermally driven cycle, unlike mechanical compression; and secondly a second liquid called the absorbent, other than the refrigerant, is what makes an absorption chiller different from a mechanical vapor compressor. This second absorbent liquid is very much important as the efficiency of the SAC and its usability in any given environment is directly linked to the liquid used as well as its concentrations.

SAC can further be classified on the basis of the number of stages in the cooling process and thus two types, single absorption chiller and double absorption chiller are in vogue. Double absorptions chiller have a high deployment and running cost whereas the single absorption chiller are relatively cheaper to install and run.

The introduction and implementation of SAC can cause huge energy savings along with energy-demand fulfillment in not only Pakistan but also other parts of the world. If interested in further reading here are a few links to get you started.

http://www.sciencedirect.com/science/article/pii/S0378778808001734

http://www.sciencedirect.com/science/article/pii/S0378778809002163

http://www.sciencedirect.com/science/article/pii/S0378778811005548

http://gradworks.umi.com/15/31/1531888.html

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Green Plumbing

Green Plumbing

We have been discussing green buildings in our building science course with an emphasis on topics such as heating and solar ventilation. We have explored advances in insulation of homes and green HVAC systems. One more facility that I have learned can be modified to be more green is the plumbing system. Reducing bills and adverse effects on the atmosphere, targeting the plumbing system would benefit us greatly. In a course on plumbing that I am taking, I learned a number of important facts and figures on how we can go green more effectively by going green in plumbing department. Below are a few areas in which residential energy use related to water and plumbing is proving costly and a few ways that can be implicated to conserve the energy being used.

Heating water for use by residents of a home accounts for approximately 30% of residential energy use. Moreover, wasted water adds up to thousands of gallons per year which wastes a lot of energy involved in water handling. If we can reduce the heat loss from hot water and conserve water, we can see a drastic reduction in bills and can contribute more effectively to going green.

Some of the things we can do to reduce the use and heating of water are as follows:

  • Low-Flow fixtures: Installing this type of over-head shower fixture can reduce the water usage in the residence by up to a staggering 60 percent by reducing the flow of water. Less water being used means less water being heated and this would prove beneficial financially as well as environmentally.
  • Faucet Flow Reducers: Similar to the concept of low-flow shower fixtures, installation of such faucet fixtures is easy considering that they can fit on the end of your current faucet fixture where the aerator is screwed on and will reduce water flow by up to a handsome 40 percent.
  • Low-Flush Toilets: About 28 gallons of water per person per day are used by the flushing of toilets. Flushing the toilet is the single most water consuming use in a home.
    Installing these types of toilets reduce the amount of water used per flush by anywhere from two to five times less than the standard toilet.
  • Home Leak Monitoring Device: This involves installing a device that will alert you when it senses a leak so that you can find and fix the issue sooner than you would without being alerted. Leaking faucets, toilets and pipes account for thousands of gallons of water being wasted monthly so such a device certainly would play a role in energy conservation.
  • Energy-Efficient Appliances: You can reduce the amount of water consumption in a residence by as much as half by installing energy-efficient dishwashers and clothes washers.

Making your home green does not just mean making it healthier for the environment but also healthier for the inhabitants of the home. A couple examples of steps to make your home healthier are as follows:

  • Installation of Chlorine Filters on Shower heads: Chlorine is readily absorbed through the skin six times faster than through the digestive system and so chlorine sensitivity can be a major issue for many. Installation of a filter would reduce chlorine levels effectively.
  • Installation of Activated Carbon Filters: These filters are installed on faucets and showerheads and absorb pollutants. If you are concerned with poor water quality this option would prove beneficial as a purification strategy.

Some of the measures we can take to reduce home energy use regarding plumbing are as follows:

  • Remove/Avoid Plumbing from Exterior Walls: Doing this and running the pipes through conditioned spaces instead will reduce the amount of heat loss from being in close proximity to the outside atmosphere and temperature.
  • Insulate Pipes: If the above mentioned strategy is not a possibility then insulation of the pipes will allow less heat loss and will definitely make a beneficial impact in your utility bill.

Resources:

http://www.homeadvisor.com/article.show.Green-Plumbing.16396.html

http://www.greenbuilding.com/professionals/green-building-practices-and-technologies/green-building-plumbing

http://www.greenbuildingadvisor.com/green-basics/green-plumbing-systems-save-water-and-energy

NIght Flushing

Maintaining the internal climate of buildings and structures while minimizing the ecological footprint as well as reducing power consumption has always been a very important part of architectural engineering. To achieve this goal of climate control an important technique being used extensively, especially useful in areas with relatively large temperature difference between days and nights; and in relation to buildings and structures constructed of material with high specific heat capacity such as bricks masonry and concrete, is called Night Flushing.

Night Flushing is an interesting use of natural ventilation. By using the natural cooling effect of the night and the cooler air at night simply allowing the cool night air to circulate a structure during the night allows the loss of the heat buildup, or heat mass gathered by the structure during the day. In order to achieve this cooling one simply needs to allow the night air to circulate the building , in simple structures by simply opening the windows during night time. The cool night air carries away the heat absorbed by the structure during the day. The very nature of concrete or other high specific heat capacity materials makes them perfect to use in conjunction with Night Flushing as the structure will take a long time to absorb enough heat during the day to change its temperature and thereby not only decreasing the cost of maintaining a stable internal climate during the day, but would also drastically decrease the cost of cooling as most of the heat absorbed during the day is lost during the night via Night Flushing. Thermal mass is a property enabling structures to absorb, retain and then release heat energy, this coupled with a high specific heat capacity means that buildings made up of concrete need to absorb a substantial amount to heat to effect a change in temperature. 1

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This simple use of natural cooling if properly incorporated in a building’s design could drastically reduce the load on HVAC and can result in substantial savings of electricity.

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This technique is not without its limitations and one of the most important cons which comes to mind immediately is security, especially in residential buildings or buildings occupied during the night. Similarly Night Flushing requires a climate with a marked difference between night and day temperatures, so its implementation is very climate dependent.

For those interested in further reading the subject here a few links to get you started.

http://en.wikipedia.org/wiki/Thermal_mass

http://www.concretethinker.com/solutions/Thermal-Mass.aspx

http://sustainabilityworkshop.autodesk.com/buildings/natural-ventilation

http://digitallibrary.usc.edu/cdm/ref/collection/p15799coll127/id/314242

Fighting the humidity in basements

Engineers have come a long way in improving the indoor air quality and comfort for inhabitants of houses. Whether it is a double story house or triple story house the HVAC systems and all the design measures ensure controlled environment yet there is one portion of the house or building that faces problems, the basement. Having a room in a basement, I have been searching for ways to solve certain problems that are very minor or not at all present in the rest of the house. Some of the problems are that there is a musty and warm atmosphere in basements during summer, while there is an extremely cold and clammy environment in basements in winter. In either weather the basement often remains humid. There are two instant and easy solutions that everyone thinks about:

  • Getting a dehumidifier
  • Membrane or coating on inside

Getting a dehumidifier seems like a good option but there are issues associated with that too. Dehumidification can be used as a means of reducing the humidity and odor in a basement, but it is not a permanent or complete solution. In fact, if a dehumidifier is used in a basement with moisture problems, it may cause greater damage. By drying out the basement air, moisture is drawn into the basement more rapidly causing efflorescence of concrete and further damage to interior finishes.

Combating basement moisture problem with a membrane or coating on the inside seems effective, however, the water is still present and eventually these systems deteriorate or simply move the water to another pathway into the basement. So what can be done to solve the problem completely? Upon further research I have understood that we can not remove the water but can channel it for our benefit. The two most important measures are depicted below:


 Appropriate Gutters, Downspouts and Accurate Grading:

A great number of basement water problems can be solved by the method as follows

  1. Sloping the grade away from houses
  2. By handling rainwater and surface drainage properly using gutters and downspouts with extenders or splashblocks to carry the water away from the foundation.

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Adequate Exterior or Interior Drainage System:                                

Exterior Drainage:

It is expensive to do this but it’s the most effective means of water proofing. The conventional exterior drainage systems use

  • Free-draining sand in the backfill.
  • Drain tile placed beside or on top of the footing.
  • A minimum of 12 inches of coarse aggregate should be placed around the drain tile.

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Interior Drainage System:

There are a couple of ways to install drainage system inside the basement. Most of them consist of either a normal or perforated drain pipe on the perimeter collecting water and dumping it to sump pump.5

Conclusion:

If we want a comfortable less humid environment in the basements we should give more importance to the drainage of water and should combine that with the use of Dehumidifiers to get the best possible result.

For more information visit these links:

http://www.familyhandyman.com/basement/drying-a-wet-basement/view-all

http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements?topic=doctypes/digests

Aesthetics and solar energy.

When we talk about energy efficient and green buildings , One of the first things that comes to mind is solar panels and solar cells. For some home owners and business owners aesthetics is an insignificant trade off when it comes to reducing energy bills and carbon emissions. But for a substantial number of people the opposite is true.  So the question to my mind has always been how to consolidate energy savings with pleasing aesthetics and to this end i am always keeping a lookout for advances and means allowing the integration of energy efficiency and looking good. Some of the things I came across include the use of colored solar panels, as well as ideas to give unique aesthetic look while using conventional solar panels.

Colored solar panels

With the advancements in technology, Solar panels which were just previously available in black and blue shades are now being manufactured in red, emerald green, forest green, and polished marble. The colored variant of the solar panels are slightly less efficient, typically 1-3% less, a downside which is easily set off by the ability to use solar panels in situations where the older variants were not aesthetically viable.

 

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Solar shingles and photovoltaic slates

Just like normal roof shingles, solar shingles are being introduced that blend in very nicely with the buildings architecture. These consists of a polycrystalline photovoltaic tempered glass module adhered to a metal shingle. 

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Solar cladding

Architects use different types of cladding to create unique and beautiful facades. One of the ways with which we can not just create beauty but also fulfill or atleast cut down the energy useage of the buildings is the solar cladding.

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Natural Air Purifiers

The course on Building Science focuses on teaching students how to improve built environments and how to provide a clean and comfortable environment for the inhabitants or users of a building.  In our class, we have discussed ways to make energy efficient environmental friendly buildings.  This motivated me to find some naturals ways for air purification. Upon investigation, I gained knowledge on a couple of natural ways that can purify indoor air that I feel people with contaminated air in their homes and work spaces would benefit from because the current technologies on air purification come with their significant detriments and disadvantages.

As we make buildings with better insulation and energy efficiency, we tend to make buildings tighter with less ability for air to pass freely. Air quality can suffer due to that. Mechanical air purifiers and filters claim to be very efficient in cleaning dust particles, smoke and other contaminants. Now there are even ones that do not even require the filters to be changed, such as ionic or ozonolysis air purifiers. These filters are able to provide clean air without the noise of previous filters with older technology.  But these mechanical air purifiers are not the ultimate solution they appear to be. These machines are not only expensive but can pose a threat to the health of those exposed to the air pollutants it ironically creates. There are about 2.2 miligrams of ozone released per hour by Ionic purifiers and 200 miligrams per hour released by Ozonolysis purifier. These amounts can cause lung disease and shortness of breath as well as asthma and throat irritation.  There are four natural easy alternatives to this scenario. Image

The first of the natural alternatives is one that we learn about in high school biology. Plants have been shown in studies conducted by NASA to have the effect of eliminating toxic waste and cleansing the air of toxins. This is done when a plant emits water vapor which creates a pump action that pulls contaminated air down towards the roots of the plant where it is used by the plant to make food; this makes for a symbiotic relationship between the building inhabitant contributing to the pollution and the plants kept in the closed space. The second of the natural alternatives is Beeswax. Yes, Beeswax candles have the effect of cleaning the air of pollutants around it by negatively charging ions when it burns which cling to positively charged pollutants and allergens in the air. Yet another easy way to clean the air in an enclosed space is by using activated carbon. Installing activated carbon into the heating, ventilating and air conditioning HVAC systems can help purify the air because it has the ability to eliminate odors and trap pollutants in its pores. A final way to purify air that I discovered in my research was the use of salt lamps. Salt lamps are made by hollowing out large chunks of salt crystals; after hollowing it out, a light bulb or candle can be placed inside.  When the salt is heated by the flame or heat, it releases negative ions just like the beeswax candle and ionic air purifier, and the ions attach to the positively charged pollutants and allergen. These four techniques are inexpensive and require little effort to maintain yet can have a significant impact on the purification of the air we breathe in some poorly ventilated buildings. The alternatives are worth considering when finding a solution to polluted air.Image

For more information visit these links:

http://www.idealhomegarden.com/holidays-crafts/best-natural-air-purifiers/

http://www.naturalnews.com/035961_air_quality_indoors_purification.html

Hybrid Solar Lighting

Sun has always been the main source of lighting however with the advent of electricity areas without direct access to sunlight have become easier to illuminate. However different methods were used for lighting the places like underground vaults, basements, storage chambers and rooms with fewer openings and direct access to sunlight. Most of these methods were based on principles of reflection and refractions, with mirrors and prisms being used to route light. But with the advent of electricity we  started relying on it for light. But given the electricity costs for lighting and heat and with the increase in environment awareness different techniques have come to the fore for reducing the impact on the environment.  One of these techniques which piqued my interest is HYBRID SOLAR LIGHTING {HSL}

Hybrid Solar Lighting (HSL) system uses artificial light in conjunction with sunlight for illumination. Sunlight is channeled into rooms without direct access to sunlight, i.e. underground rooms or rooms without windows or skylights, using Optical Fibers and supplemented by artificial or electrical lights where required, thereby reducing the running costs for lighting areas with electricity alone.

HSL consists of a collection unit, usually placed in an area with direct sunlight such as rooftops, which focuses the sunlight onto Optical Fibers. The flexible optical fibers then convey the lights to hybrid light fixtures, called luminaries, which are built to diffuse the sunlight and provide lighting in all directions. The setup is called hybrid because it also uses artificial light to supplement sunlight where required. The amount of artificial light can be monitored using a photoelectric light sensor.                                                            

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An HSL made up of 4ft wide collector and 127 optical fibers can adequately light up an area of around 1000 sq ft.

Advantages.

It is a good way to save energy and cost. The cost is not just saved from the reduced artificial lighting but also from the reduced cooling requirement in hot climate because Infra-red and ultraviolet part of sunlight is not transmitted to the interior. Moreover it also means reduced Carbon dioxide emissions. The light that penetrates and comes from the optical fiber is full spectrum unlike most bulbs which only provide narrow band of light. Unlike solar panels , HSL systems have high efficiency because most of the light energy is transmitted through the fiber optics unlike solar panels where a lot of energy is lost .

Disadvantages.

One of the setback of this technology is the initial cost. It almost costs $40, 000 to light up to 10,000 sq ft. But I believe with the advancement of technology it will come down. In 2012 students of university of Maryland used this technology and figured out the payback time is almost three years if they light up a hall.

So we can think of it as a step towards lighting buildings while being environment conscious.