UNIVERSITI MALAYSIA PERLIS

UNIVERSITI MALAYSIA PERLIS

EAT 257 BUILDING SERVICES ENGINEERING Khairul Nizar IsmailLecture 3

(28 Febuary 2013)

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Transport baseline fuel consumption in EC (2007) Current trends both regionally & globally are likely to threaten the earths climate as well as energy securityTransport fuel use trendsOil, Gas and Energy:Myths and Realities6Oil & Gas Industry MythsThe world is running out of oil and gas.The industry determines the price of oil and natural gas.The industry is low tech.The industry is environmentally insensitive.Oil and gas can be easily and economically replaced with renewables in the next few years.There is no future working in the petroleum industry.Quality of life and GDP are not significantly influenced by energy use.

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Myth #1: The world is running out of oil and gas.

Reality #1: Oil and Natural gas will continue to be the primary energy sources for years to come. Unconventional oil and gas will become increasingly more important.8World Demand for Fossil Fuels Will Continue to Grow Source: EIA, World Energy Outlook 2008

World energy demand expands by 45% between now and 2030 an average rate of increase of 1.6% per year with coal accounting for more than a third of the overall rise 9Fossil fuels continue to supply ~ 80 percent of worlds energy

Source: EIA World Energy Projections Plus (2008)HistoryProjectionsPrimary Energy Demand (1015 btu)

20102015 20202025 2030 Petroleum 181 194 206 216 230 Natural Gas 120 134 147 156 165 Coal 140 158 172 187 202 Nuclear 29 32 35 38 39 Other 42 45 49 55 59

Source: Energy Information Administration, U.S. Department of Energy 11

Source: BP Statistical Review of World Energy 2008

Proved oil reserves at end 2007Thousand million barrelsEnergy Supply SummaryOver the next 25 years, oil and gas demand will rise dramatically, primarily in developing countriesExpansion of all economic energy sources will be required: coal, nuclear, biomass, other renewables, unconventional oil and natural gas. Each source faces significant challenges...

Oil and gas supplies:Most conventional oil and gas is located in remote, potentially unstable areasThe bulk of new supply will have to come from more expensive mature assets and unconventional resources13

2050NOWNate Lewis: Cal TechSolar Energy Production165,000 TW of sunlight hit the earth every day14Area that has to be covered by present - efficiency solar cell to produce 3 and 20 Terawatts/hr. respectively.3 TW is close to the total electric energy of the USA

The Potential of Geothermal Energy15Questions?16THERMAL COMFORT

THERMAL COMFORTHuman thermal comfort is defined by ASHRAE as the state of mind that expresses satisfaction with the surrounding environment (ASHRAE Standard 55). Maintaining thermal comfort for occupants of buildings or other enclosures is one of the important goals of HVAC design engineers.Thermal comfort is affected by heat conduction, convection, radiation, and evaporative heat loss. Thermal comfort is maintained when the heat generated by human metabolism is allowed to dissipate, thus maintaining thermal equilibrium with the surroundings. Any heat gain or loss beyond this generates a sensation of discomfort. It has been long recognised that the sensation of feeling hot or cold is not just dependent on air temperature alone.

Factors determining thermal comfort :

Metabolism Insulative clothing Relative humidity

Metabolism

When measuring metabolism rates, many factors have to be taken into account. Each person has a different metabolism rate, and these rates can fluctuate when a person is performing certain activities, or under certain environmental conditions. Even people who are in the same room can feel significant temperature differences due to their metabolic rates, which makes it very hard to find a optimal temperature for everyone in a given location. Clothing insulation

During cold weather, layers of insulating clothing can help keep a person warm. At the same time, if the person is doing a large amount of physical activity, lots of clothing layers can prevent heat loss and possibly lead to overheating. Generally, the thicker the garment is the greater insulating abilities it has. Depending on the type of material the clothing is made out of, air movement and relative humidity can decrease the insulating ability of the materialRelative humidityThe human body has sensors that are fairly efficient in sensing heat and cold, but they are not very effective in detecting relative humidity. Relative humidity creates the perception of an extremely dry or extremely damp indoor environment. This can then play a part in the perceived temperature and their thermal comfort. The recommended level of indoor humidity is in the range of 30-60%.

After completing this Lesson, you will be able to answer:

1. What is humidity? 2. What is relative humidity? 3. How relative humidity is measured? 4. What is a Hygrometer? 5. How Wet- and Dry Bulb Psychrometer and Hair Hygrometer measure relative humidity?

Humidity refers to the amount of moisture (water vapor) in the surrounding air.

Relative Humidity is a measure of the amount of moisture in the air compared with the amount of moisture the air can hold.

Relative humidity is expressed as a percentage of how much moisture the air could possibly hold at the temperature it happens when you measure it.

The "wetter or damper" you feel,, the higher is the relative humidity. If you feel the air is dry around you, the relative humidity is low.

We are very sensitive to humidity. Sweating keeps our body cool and maintain its current temperature.

If the air is at 90% relative humidity, sweat will not evaporate into the air. As a result, we feel much hotter than the actual temperature when the relative humidity is high.

If the relative humidity is low, we can feel much cooler than the actual temperature because our sweat evaporates easily, cooling the body.Definitions of Relative HumidityA term used to describe the quantity of water vapor in the air as a ratio of the maximum amount that the air can hold at that temperature.A ratio that compares the amount of water vapor in the air with the amount of water vapor that would be present if the air was saturated. Relative humidity is the ratio of two pressures: %RH = p/ps x 100where p is the actual partial pressure of the water vapor present in the ambient and ps the saturation pressure of water at the temperature of the ambient.

Example of Relative HumidityOne way it can be stated is as the ratio of the actual mixing ratio to the saturation mixing ratio. For example: If 10 grams of water vapor were present in each kg of dry air, and the air WOULD BE saturated with 30 grams of water vapor per kg of dry air, then the %RH would be:10 / 30 = 33.3%

How relative humidity (RH) is measured?

Humidity is measured by means of a hygrometer.

There are different types of hygrometers.

The most common hygrometers are Wet- and Dry- Bulb Psychrometer and Hair Hygrometer.

How relative humidity (RH) is measured?Wet- and Dry Bulb Psychrometer

Wet - and Dry Bulb Psychrometer

How relative humidity (RH) is measured?

Wet- and Dry Bulb Psychrometer Psychrometric Chart. If the difference between wet and dry bulb is 6 F and the temperature is 72 F (dry bulb), then the RH is 54%.

How relative humidity (RH) is measured?

Hair HygrometerHumidity stretches the hair (human / animal / synthetic) while dryness shortens it.

The hygrometer has the job of stretching a hair between a fixed and a movable point to measure humidity over time.

Hair Hygrometer

How relative humidity (RH) is measured?

Other kinds of hygrometers use materials with electrical resistance that varies with the amount of moisture absorbed.

With such hygrometers, a measurement of electrical resistance can be calibrated as a humidity measurement.

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LiquidsNatural GasCoalNuclearRenewables

Sheet1Column1LiquidsNatural GasCoalNuclearRenewables1980131.054.070.37.620.91981125.954.171.48.521.51982122.754.272.79.522.11983120.955.374.610.723.41984123.161.079.013.024.01985123.163.682.415.324.31986127.264.383.816.324.81987129.667.786.417.624.81988133.671.189.019.225.51989135.474.389.019.725.81990136.475.289.220.426.21991137.476.686.121.226.91992137.976.885.521.327.01993137.779.086.722.028.21994140.178.887.522.428.71995142.481.088.523.330.01996145.684.690.124.130.71997148.984.892.623.931.01998150.385.890.824.330.91999153.288.191.725.131.62000155.291.393.525.732.32001156.592.795.026.431.52002157.696.198.326.731.82003161.099.7107.026.532.42004166.6103.3116.127.433.82005169.4107.4122.527.535.52006171.9109.3125.827.936.92007173.9112.9129.528.238.02008176.4115.4132.728.439.62009178.6118.0136.428.640.52010181.1120.3140.228.842.02011183.9123.2144.029.442.72012186.8126.1147.429.943.22013189.4128.7150.830.443.92014191.9131.5154.330.944.42015194.4134.4157.831.545.02016196.9137.2160.532.045.82017199.3139.7163.432.546.62018201.6142.1166.033.147.42019203.9144.4168.933.848.32020206.1146.9171.734.549.32021207.9148.8175.335.150.52022210.2150.6177.935.851.72023212.4152.3180.936.452.72024214.7154.1183.737.153.72025216.9155.8186.737.754.72026219.4157.6189.938.255.62027221.8159.4193.038.656.52028224.2161.2196.138.957.42029226.7162.9199.139.258.22030229.3164.7202.239.559.0To resize chart data range, drag lower right corner of range.

Chart140.8Asia PacificAsia Pacific69.3North AmericaNorth America111.2South & Cent. AmericaSouth & Cent. America117.5AfricaAfrica143.7Europe and EurasiaEurope and Eurasia755.3Middle EastMiddle East

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Sheet1Column1Column2Column3Column4Asia Pacific40.8North America69.3South & Cent. America111.2Africa117.5Europe and Eurasia143.7Middle East755.3To resize chart data range, drag lower right corner of range.