Determining a building energy needs Providing heating and cooling - PowerPoint PPT Presentation

Determining a building energy needs Providing heating and cooling using geothermal John Waitt Design Day Mechanicals

International Energy Conservation Code IECC 2009 Zone Ratings 1 ‐ 7 in Continental US • Maine ‐ Zone 6 and Aroostook is Zone 7 • NH ‐ Zone 5 and 6 This applies to both Residential and Commercial Buildings. Many States have made their code even more stringent

• Leadership in Energy and Environmental Design ( LEED ) is a third ‐ party certification program. It is a nationally accepted organization for design, operation and construction of high performance green buildings. • Energy Star is an international standard for energy efficient consumer products originated in the United States. It was created in 1992 by the Environmental Protection Agency and the Department of Energy. Devices carrying the Energy Star service mark, such as computer products and peripherals, kitchen appliances, buildings and other products, generally use 20–30% less energy than required by federal standards.

Explanation of Zone and Why • The need for zones determines rates of insulation and equipment selection as a result of weather statistics • Residential and commercials building have different envelope guidelines • Equipment selection ‐ Based on capacities and efficiencies and the zone in which they are being used.

Envelope Guidelines • Commercial Simplified ‐ Zone 6 Walls ‐ Metal Building ‐ R ‐ 13 + R ‐ 5.6ci Roof R ‐ 20ci Slab ‐ R ‐ 10 for 24” below

Envelope Guidelines • Residential ‐ Zone 6 Walls ‐ Wood Frame ‐ R ‐ 20 or R ‐ 13 (cavity) + R ‐ 5 (insulated sheathing) • Roof/ Ceiling ‐ R ‐ 49 • Basement ‐ R ‐ 15/ 19 ‐ (continuous/ cavity)

Interior Design Conditions • Heating 72 Deg F Maximum • Cooling ‐ 75 Deg F Minimum Leeway can be allowed if the designing engineer feels it valid. • Health Clubs, IT/ Computer, Archives

Load Calculations • All of the above criteria are used to determine how much energy a building needs and what is the design days requirement. (the expected extremes at either end of the range. • Knowing the design days need’s lets you select the size of equipment you need.

Building Examples • Commercial Building, two Floor, 6000+ sq. ft. • Heating needed ‐ 117,00 btus; 19.34 btu/ sq ft • Cooling needed ‐ 13.5 Tons; 448 cfm/ sq ft • Residential Structure. Two floors, 2240 sq. ft. • Heating needed ‐ 64,338 btus; 28.72 btu/ sq ft • Cooling needed ‐ 6 tons; 373 cfm/ sq ft

Energy Choices • Oil ‐ 138,000 btus/ gallon • Natural Gas ‐ 100,000 btus/ therm • Propane ‐ 92,500 btus/ gallon • Resistance electric heat ‐ 1 kW in 1 kW out • Electric using heat pumps

Btus per $ based on efficiencies • Btus/ unit divided by $/ unit= BTUs/ $ • Example ‐ Oil boiler at 83% efficiency (138,000 btu/ gal x .83= 114540 btus. • 114540 btu per gal/ $1.73 gallon= 66,208 btus/ $ ( @ $2.50=48,816: @ $3.00=38,180) • Propane @ $2.24 per gallon and 95% efficient= 39230 btus/ $

• Natural Gas ‐ @ $1.10 per therm (100,000 btus) and 95% efficiency = 86,364 btus/ $ • Electricity; Resistant heat ‐ 100% efficient Rates vary around state ‐ @ $0.14/ kW ( 1 kW is 3414 btus)= 24,386 btus/ $. • Electricity; Heat Pumps ‐ @ $.014/ kW. Heat pumps are rated for heating by Coefficient of Performance.

Coefficient of Performance • The COP of a heat pump is a ratio of heating or cooling provided to work required. Higher COPs equate to lower operating costs. The COP may exceed 1, because, instead of just converting work to heat (which, if 100% efficient, would be a COP of 1), it pumps additional heat from a heat source to where the heat is required.

• Heat pumps ‐ Air to Air; Water/ fluid to Air ‐ Water source, ground water source or Ground source. • Water source ‐ Cooling tower and boiler • Ground Water source ‐ Standing Column well • Ground source ‐ filled bore holes

• Typical residential/ light commercial “small” heat pump 3/4 to 5 ton ‐ has a COP ranging from 3.4 ( ¾ ton) at 30 deg entering fluid to 3.7. What this means is that for every 1kW provided you get 3.4 to 3.7 kW out.

• 3414 btus/ 1kW x 3.7 COP/ $0.14 per kW= 90,227 btus/ $. • If the fluid temperature is higher, 50 Deg F, then the COP for 5 tons is 4.5 and you get 109,736 btus/ $.

Oil vs. Heat Pumps yearly cost • Commercial Building • Oil at $1.73/ gallon and electricity @ $0.14= $5278 vs. $4594. $683 in savings. • Oil at $2.50/ gallon and electricity @ $0.14= $7208 vs. $4594. $2614 in savings.

Oil vs. Heat Pumps yearly cost heating and cooling • Residential Building • Oil at $1.73/ gallon and electricity @ $0.14= $3549 vs. $2445. $1104 in savings. • Oil at $2.50/ gallon and electricity @ $0.14= $4943 vs. $2445. $2497 in savings.

Using the earth • Standing Column Wells. These are similar to domestic water wells, where you are looking for water to help with heating and cooling. • Closed Loop Bore Holes. These do not need water directly, but instead use the rock as a radiator.

• Closed loops need greater surface area into the earth, but do not need to find water. • Close loop systems can utilize a greater temperature range to provide heating and cooling • Anti ‐ Freeze is need to use the lower temperature, and the lower the temperature of the fluid, the less heat that can be extracted. The HP provides less heat and therefore needs to be selected large enough to handle the lower at its lowest capacity.

• Standing column wells • If there is good water flow, the system using a standing column well does not need as much depth into the earth to provide adequate capacity. • The “heat” in the water is used. If the water temperature gets beyond the operational range of the heat pump then water is bled off, and like a regular well new water flows in and adjust the temperature.

Refrigerant Cycle. How Heat Pumps work • All AC units are heat pump. A window unit set to always send hot air out the window in summer, and cold air into the building. • The refrigerant cycle is a closed loop system. Liquid is pumped to a coil where there is a pressure change and the liquid evaporates and in doing so, extracts heat from the air. The liquid is now a gas.

• To allow the cycle to continue, the gas is compressed and then condensed back into a liquid in a coil. This process rejects heat into the air. • A unit defined as a heat pump, has a valve within the unit that switches the refrigerant flow.

• Summer=heat outside/ cold inside • Winter=heat inside/ cold outside • The limit to this air to air system is the outside air can get very cold or very hot thus affecting the capacity and efficiency • Water or earth system have a more steady range of temperatures and not the extremes of air.

Examples of standing column “issues” • 6 story dorm in downtown Manchester, NH. • 3 wells planned but low water flows. Two drilled and system redesigned to use domestic water boilers. Balancing flow issues. • Elderly Housing residence • 3 wells planned and drilled, but too much water. One well continually over flowed. Causing wet grounds.