Residential HVAC Manual J Load Calculation, written by Air Conditioning Contractors of America (ACCA), is the approved procedure to properly calculate the required size of a HVAC system for a residential home. By utilizing the Manual J8 Load Calculation you set yourself apart from your competition by guaranteeing your customer will have the industry standard in home heating and cooling efficiency, thus keeping their energy costs to a minimum. It is very important to size the HVAC system properly. If the unit is undersized, it will not condition the home fast enough, on the other hand, if it is oversized, it will condition the home too fast without properly dehumidifying the room. Often HVAC contractors use “rules-of-thumb” to figure out the size of the HVAC system, without considering some important variables such as, the internal heat loss and gain, humidity, building orientation, ventilation and infiltration, resulting an overly-sized HVAC system. This issue is called “short cycling.” Undersized HVAC equipment is always running and will never satisfy the required temperature. The undersized equipment will not last as long as an accurately sized system. It is more cost-effective to size a comfort system according to the average winter or summer condition while deciding the outdoor design temperature, instead of designing for the rare “worst-case-scenarios.” Residential Manual J8 methods is not appropriate for high rise, commercial and industrial buildings, a room with an indoor hot tub or swimming pool, and houses that use passive solar methods. In any ACCA Certified Manual J load calculation, the following items need to be addressed: · Use the actual orientation of the residence. Solar heat gain depends on the orientation. · Get the exact construction material R-values · Properly evaluate the infiltration load and required ventilation load following Manual J8 procedures. · Use design conditions recommended by ASHRAE or Manual J8. According to ACCA, the indoor dry bulb temperature should be 70oF for heating and 75oF for cooling. The indoor relative humidity (RH) for cooling should be 50% for wet climates and 45% for dry climates. · Include curtains, drapes and blinds because they can change the r-value of the glazing. · Include overhangs - “By including the overhang benefit in the analysis, the projected cooling load can be reduced to a ton on a 2400 ft2 home” (Addendum A to ACCA Manual J). · Include the people internal gain from a residence, which is assumed to be the # of bedrooms + 1. HVAC installers can save huge amounts of time & money on costly mistakes when installing HVAC systems in a home by hiring a to do the Manual J load calculations. There are many crucial benefits to the customer in hiring an ACCA Certified Manual J8 Load specialist: HVAC design experience, ACCA certified Manual J software experience, turnaround time, and customer service. WrightSoft Universal 7.0 software is one of the most recognized Manual J Load Calculations software programs for EnergyStar, building permit code compliance, LEED Certification, Build Green projects and EEM. Make sure your HVAC installer or Manual J8 Load Calculation provider is not using a cheap, non-ACCA certified software to calculate your residential Manual J8 project summary or it could be declined. The Air Conditioning Contractors of America (ACCA) Manual J8 Residential Load Calculation Procedure is the accepted industry standard for the proper sizing and selection of HVAC equipment in residential applications. Manual J outlines the accurate procedure which can be used to calculate the heat loss and heat gain for conventional residential structures. Make sure your Load Calculation Reports are based on ACCA's Manual J 8th Edition, inclusive of all four addenda to the 8th edition. Lastly, huge price profits can be had in using an in every home you build by choosing the right sized HVAC system. An ACCA Certified Manual J Load Calculation provider can help set you apart from your competition by guaranteeing your customer will have the industry standard in home heating and cooling energy efficiency, keeping their costs and yours to a minimum.