How To Input Lighting Information In Hap

Frequently Asked Questions: Entering Lighting Information in HAP

This guide answers common questions about inputting lighting information into Carrier's Hourly Analysis Program (HAP) software. Accurate lighting data is crucial for precise energy consumption and HVAC load calculations. We aim to provide clear and concise answers to help you effectively utilize HAP for your building energy modeling needs.

Question 1: Why is Accurate Lighting Information Important in HAP?

Accurate lighting data is essential in HAP because lighting contributes significantly to a building's internal heat gain. This heat gain impacts the cooling load, affecting the size and energy consumption of your HVAC system.

• Underestimating lighting loads can lead to an undersized HVAC system, resulting in insufficient cooling and discomfort.
• Overestimating lighting loads can lead to an oversized HVAC system, increasing initial costs and potentially leading to inefficient operation.
• Correct lighting input ensures HAP's calculations reflect real-world conditions, allowing for more accurate energy simulations and better informed HVAC design decisions.

In short, accurate lighting data directly influences the accuracy of your energy analysis and the effectiveness of your HVAC system.

Question 2: What Lighting Information Do I Need to Gather Before Using HAP?

Before you start entering lighting information into HAP, you'll need to gather the following data for each space or zone in your building:

• Lighting Power Density (LPD): This is the amount of power (in watts) consumed by lighting per square foot (W/ft²) or square meter (W/m²) of floor area. You can determine this from lighting design plans, fixture specifications, or through a lighting survey of the existing building.
• Operating Schedule: This defines when the lights are on and off throughout the day and the week. You'll need to specify the hours of operation and any variations in the schedule for different days of the week or seasons.
• Fraction of Lighting Load to Space: This indicates the percentage of the total heat generated by the lighting that is released into the conditioned space. Typically, this value is 1.0 (100%), meaning all the heat from the lights goes into the space. However, if fixtures are vented or partially located outside the conditioned space, this fraction will be lower.
• Fixture Type (Optional): While not always required, specifying the type of lighting fixture (e.g., fluorescent, LED, incandescent) can improve accuracy, especially when using HAP's built-in lighting performance data.

Having this information readily available will streamline the input process and minimize errors.

Question 3: Where Do I Enter Lighting Data in HAP?

Lighting information is typically entered in HAP within the Space or Zone definition. The specific location may vary slightly depending on the version of HAP you are using, but the general process is similar:

1. Open the project file in HAP.
2. Navigate to the "Spaces" or "Zones" section.
3. Select the space or zone for which you want to enter lighting information.
4. Look for a tab or section labeled "Lighting," "Internal Loads," or something similar.
5. Within this section, you will find fields for entering the Lighting Power Density (LPD), Operating Schedule, and Fraction of Lighting Load to Space.
6. Enter the appropriate values for each field.
7. Save the space or zone definition.

Refer to the HAP help documentation for detailed instructions specific to your version of the software.

Question 4: How Do I Determine the Lighting Power Density (LPD) if I Don't Have Design Plans?

If you don't have design plans or fixture specifications, you can estimate the Lighting Power Density (LPD) through a lighting survey. Here's how:

• Inventory the Lighting Fixtures: Count the number and type of lighting fixtures in the space. Note the wattage of each lamp or bulb in each fixture.
• Calculate Total Lighting Power: Multiply the number of fixtures of each type by the wattage of the lamps in those fixtures. Sum the results to get the total lighting power in watts.
• Measure the Floor Area: Measure the floor area of the space in square feet (ft²) or square meters (m²).
• Calculate LPD: Divide the total lighting power (in watts) by the floor area (in ft² or m²). This will give you the LPD in W/ft² or W/m².

Example: A room has 10 fixtures, each with two 40-watt lamps. The total lighting power is 10 fixtures * 2 lamps/fixture * 40 watts/lamp = 800 watts. If the room's floor area is 400 ft², the LPD is 800 watts / 400 ft² = 2 W/ft².

You can also consult building codes or industry standards (like ASHRAE Standard 90.1) for prescriptive LPD values for different building types and space functions. These values can serve as a reasonable estimate if a detailed lighting survey is not feasible. However, using actual measured values is always more accurate.

Question 5: How Do I Create or Select an Appropriate Lighting Operating Schedule in HAP?

HAP provides a built-in library of standard operating schedules, and you can also create your own custom schedules. To create or select a schedule for lighting:

• Review Existing Schedules: Explore the existing schedules in HAP to see if any closely match the actual lighting usage patterns in your space. Common schedules include "Office Hours," "Retail Hours," and "24/7 Operation."
• Create a Custom Schedule (if needed): If none of the existing schedules are suitable, create a custom schedule. You'll need to define the fraction of lighting power that is on during each hour of the day for each day of the week. For example:
  • Monday-Friday, 8:00 AM to 5:00 PM: 1.0 (100% on)
  • All other hours: 0.0 (0% off)
• Consider Occupancy Sensors: If the space has occupancy sensors that automatically turn off the lights when no one is present, factor this into your schedule. This will require estimating the average occupancy rate and adjusting the lighting schedule accordingly.
• Account for Daylighting: If the space has significant daylighting, consider reducing the lighting power during daytime hours to reflect the reduced need for artificial lighting. This is more complex and may require using HAP's daylighting modeling capabilities.

Accurate operating schedules are vital for realistic energy simulations. Spend time carefully assessing the actual lighting usage patterns in your building to create or select the most appropriate schedules.

Question 6: What Does "Fraction of Lighting Load to Space" Mean, and How Does It Affect Calculations?

The "Fraction of Lighting Load to Space" represents the percentage of the total heat generated by the lighting fixtures that is released directly into the conditioned space. The remaining heat is assumed to be dissipated elsewhere, such as into the ceiling plenum or outside the building.

• Typical Value: In most cases, this value is 1.0 (or 100%), meaning all the heat from the lights enters the space. This is common for recessed lighting fixtures and surface-mounted fixtures in well-insulated ceilings.
• Lower Values: If the lighting fixtures are vented or partially located outside the conditioned space (e.g., some industrial fixtures or decorative lighting), the fraction will be lower. Determining the exact fraction can be challenging and may require consulting fixture specifications or performing thermal measurements.

Impact on Calculations: A lower "Fraction of Lighting Load to Space" reduces the amount of heat gain attributed to lighting within the conditioned space. This can lead to a lower calculated cooling load and a potentially smaller HVAC system. However, using an inaccurate value can lead to errors in the energy simulation. If you are unsure, it is generally conservative to assume a value of 1.0, unless you have specific information indicating otherwise.

Question 7: Are There Any Common Mistakes to Avoid When Inputting Lighting Data?

Yes, here are some common mistakes to avoid when entering lighting data into HAP:

• Using Incorrect Units: Ensure you are using the correct units for Lighting Power Density (W/ft² or W/m²) and floor area (ft² or m²). Mismatched units will result in significant errors.
• Overlooking Operating Schedules: Using a generic or default operating schedule that doesn't accurately reflect the actual lighting usage patterns can significantly skew the results. Take the time to develop or select realistic schedules.
• Ignoring the "Fraction of Lighting Load to Space": Assuming this value is always 1.0 without considering the fixture type and installation can lead to inaccuracies, particularly for vented or partially exterior lighting.
• Not Updating Lighting Data After Retrofits: If you upgrade your lighting system (e.g., replacing fluorescent lights with LEDs), remember to update the lighting data in HAP to reflect the new LPD and energy consumption. Failing to do so will invalidate your previous simulations.
• Neglecting Daylighting Effects: While more complex to model, ignoring the impact of daylighting can lead to overestimating lighting loads, especially in spaces with large windows.
• Rounding Errors: When calculating LPD or entering schedule fractions, avoid excessive rounding, as small errors can accumulate and affect the overall accuracy of the simulation.

By being mindful of these common pitfalls, you can ensure that your lighting data input in HAP is as accurate as possible, leading to more reliable energy simulations and better HVAC design decisions. Always double-check your input data and consult the HAP help documentation for specific guidance.