# Presentation: 127415

## Cooling Climates TechnologiesHawaiian Investigations2001 National Workshop on State Building Energy Codes

- July 18, 2001Howard WiigState of Hawaii&
- Erik Kolderup, PEEley Associates

## Cooling Climates Technologies

- _High performance windows_
- _Heat pipes (and other dehumidification options)_
- _UV lamps_
- Roof Color, Insulation, and Radiant Barriers
- Daylighting & controls

## Goal of Work

- Develop commercial building guidelines
- Identify potential energy code upgrades

## High Performance Windows

- Low solar heat gain coefficient (SHGC)
- High visible light transmittance (Tvis)
- Technologies:
- Coatings
- Tints

## Transmission Properties of Different Glass Types

**Visible**

**Infrared**** ****(heat)**

**UV**

## Specularly-Selective Glazings

**Blue or green tint**

**Heat Mirror**

**Low-e coatings**

**Some****retrofit window films**

**Notes:**
Some of the windows that are best in warm climates are shown here.  
Blue or green tints are better than bronze or gray.
Low-e coatings are available in types that block solar heat gain.  But not all are appropriate in the Philippines.
A special configuration of low-e coating is Heat Mirror...
For existing buildings, there are some specularly selective window films that can be applied to the glass.  These block heat without blocking too much of the view.

## Life-Cycle Cost Methodology

- Analysis accounting for:
- Cooling energy (DOE2.1E)
- Lighting energy including daylighting (DOE2.1E)
- HVAC system size (DOE2.1E) and cost
- Glazing cost (ASHRAE/T24 and CADMAC costs with additional 30% markup)
- Similar to LCC approach used for current Hawaii code
- Also  for Standard 90.1-1999 and CA standard

## Glazing Types Considered

## Example Fenestration Electricity Impact

## Electricity Impact

## Life-Cycle Cost Comparison

## Life-Cycle Cost Comparison – West Orientation

## Life-Cycle Cost Comparison – North Orientation

## Optimal Glazing Results 

- Same result for all orientations and glass areas
- High performance tint outer pane with low-e coating
- Clear inner pane
- SHGC = 0.21
- VLT = 0.35
- (without overhangs or other shades)

## Window Criteria for Hawaii

## California 2001 Nonresidential Window Requirements

- Maximum SHGC

## Windows Conclusions and Next Steps

- High performance spectrally selective windows appear cost effective in Hawaii
- Potential for more stringent window requirements in Hawaii
- Continuing analysis should include:
- Impact of shading – exterior and interior
- Impact of other orientations – NE, SE, SW, NW
- Additional window types

## Pop Quiz (multiple choice)

- A “heat pipe” is defined as...
- a heat recovery device
- a conduit for heat generated by a heat pump
- a police crowd-control weapon
- the opposite of “peace pipe”
- a & c
- b & d
- c & a
- a, b, c, & d
- x, y & z

## Dehumidification

- Humidity control important in Hawaii
- Required all year
- IAQ
- 40% to 60% RH desired for comfort
- < 60% RH to prevent mold growth
- Material degradation and maintenance
- Energy consumption

## Current Status In Hawaii

- Most cooling systems designed to meet humidity requirements at full load
- Usually don’t dehumidify adequately at partial load
- Many systems are oversized
- Mildew problems are common
- Some critical applications use electric reheat, at high energy cost
- Some use more efficient systems

## Dehumidification Alternatives

- Standard cooling system
- Does not provide enough dehumidification at low load
- Standard cooling with reheat
- Good humidity control, but high energy consumption
- Heat pipe or run-around coil
- Precools and reheats supply air
- Dual-path system design
- Separate cooling coil for outside air
- Refrigerant subcooling
- Improves dehumidification of packaged DX systems
- Desiccant systems

## Heat Pipe

- Source:  Heat Pipe Technology, Inc.

## Heat Pipe

- Source:  Heat Pipe Technology, Inc.

## Source: Carrier

## Desiccant Dehumidification

## Standard Cooling With Reheat

- 50% cooling load conditions

## Run-Around Loop or Heat Pipe

- 50% cooling load conditions

## Dual Path System

- 50% cooling load conditions

## Dehumidification Energy Comparison

## Dehumidification Code Questions

- What can and should be codified?
- What should be limited to guidelines?
- Reheat limitations?
- More important as IAQ becomes a bigger issue
- More stringent load calculation and system sizing requirements?
- Avoid oversizing cooling capacity
- Part-load system efficiency/performance requirements?
- Problem: still need cold air for dehumidification, but too cold for space conditions

## Preliminary Observations and Conclusions

- If further study shows that alternatives are more cost effective, then stricter reheat limitations will be recommended.
- Difficult balance between limiting energy consumption and encouraging IAQ

## Ultraviolet Germicidal Irradiation (UVGI) 

- Look like linear fluorescent lamps
- UV-C, wavelength of 0.2537 microns
- Penetrates germ cells, destroys DNA info
- Two primary applications
- Prevent mold growth on cooling coils
- Coverage of about 4 ft2 coil per 24 inch lamp
- Kill organisms in air stream
- Requires much higher light intensity
- Tuberculosis control

## Slide 34

## Iolani School, Honolulu

- 35,000 ft2 office and classroom building
- Six AHUs, total of 45,000 cfm
- 20 UV lamps total
- Lamps last 1.5 years
- Replacement cost approx. $1,300/year
- Eliminated mold growth and odor
- Maintenance savings $8,000 per year
- Report fewer complaints of respiratory problems
- Facility manager very satisfied

## Preliminary Observations and Conclusions

- All Hawaiian cooling coils grow mold!
- Cleaning required 1 to 2 times per year
- UV lamps effectively inhibit mold growth on cooling coils
- Primary benefits are:
- Improved IAQ
- Lower maintenance cost (less cleaning required)
- Less frequent use of potentially toxic cleaning chemicals
- Energy benefits are small
- (But mold probably reduces system cooling capacity)
- Most important applications
- Areas with dirty/dusty air
- Spaces with health concerns
- Code Issues
- More appropriate for IAQ standards
- Probably not appropriate as mandatory requirement

## Slide 37