Von Löwen Designs

Install Effective Ductwork.

Poorly designed and installed ductwork lowers heating and cooling system efficiency and capacity, and can contribute to poor indoor air quality and comfort problems.

Consider having ducts tested for airflow and leakage before and after any new work on the HVAC system. The following six strategies will improve ductwork effectiveness:

· Install new ductwork within conditioned spaces

Install any new ductwork inside the insulated envelope of the home. The unit and the duct runs may be installed in closets, chases, and soffits purposefully designed to accommodate them, or they may be installed in an attic that is insulated at the roof deck (unvented attic).

· Use duct mastic on all ducts and joint seams

Leaks in the joints between ductwork have been shown to allow, on average, 20 to 30 percent of conditioned air to leak. Leaky air ducts can cause negative pressure in the house, which can draw many outdoor and indoor contaminants into the home, including carbon monoxide from gas water heaters and furnaces. Don’t use duct tape to seal ducts; it loses its effectiveness in a few years. To maintain a tight seal for decades, use a water-based mastic at every duct joint and seam or have professionally installed aerosol sealant sprayed into the ducts.

· Install ductwork under attic insulation (buried ducts)

As a low cost alternative to installing ductwork in conditioned space, the insulation value of ductwork can be significantly improved by burying ducts in loose-fill ceiling insulation. For this approach to be most effective, duct connections must be tightly sealed.

Instead of suspending ducts from rafters or trusses, allow ducts to lay over ceiling joists or the bottom chord of trusses and blow insulation over them. To achieve moderate coverage, insulate to at least R-38. Using supply boots with side instead of top connections keeps ducts low and aids burial.

· Pressure balance the ductwork system

When a bedroom door is closed, it typically cuts off the return airflow path. This restricts air movement, leading to comfort problems and a pressure imbalance, with the bedroom pressurized and the rest of the house depressurized. This may cause infiltration of contaminated air from the attic or crawl space, or backdrafting of combustion appliances. Install an additional return duct in the master bedroom and other large rooms that can be closed off with a door. Or install a jump duct or transfer grille between the hall or main living area and these rooms with doors.

· Protect ducts during remodeling and clean all ducts before occupancy

Debris and dust from construction can lodge in HVAC units and the ductwork, potentially causing occupants to have allergic reactions and reducing the effectiveness of the blower fan and heating/cooling elements. As soon as the ducts are installed, completely seal off each duct register and the HVAC unit to block out any construction dust. Use methods and materials that will stay in place under the abuse of a typical construction site. After construction is completely finished, vacuum the blower unit and ductwork as necessary.

· Insulate existing ductwork

Insulate, to present building code levels or greater, any existing ductwork that is accessible and has no insulation or damaged insulation.

Effective ductwork practices significantly reduce energy loss, minimize indoor air quality problems and improve occupant comfort.

Install High Efficiency HVAC Filter.

HVAC filters remove particulates from the air. MERV, or Minimum Efficiency Reporting Value, is a metric used to measure an air filter’s efficiency. The MERV Rating Chart ranges from 1 to 20. The higher the MERV number, the more efficient the filter is a removing particulates.

Use HVAC air filters with a MERV rating from 10 – 13. These filters are recommended for cleaner air without compromising the performance of standard mechanical systems. Filters with MERV ratings of more than 13 create too much resistance to airflow, because the filter media becomes denser as efficiency increases. Only use a filter with a MERV greater than 13 if the HVAC system is specifically designed for it.

Clean or replace the filter regularly. Dirty filters reduce air flow and make the HVAC equipment work harder.

The EPA has identified microparticulates as a leading cause of respiratory discomfort. By reducing these particles in the indoor air, a high efficiency filter protects the HVAC equipment and makes the living space healthier.

For more information on maintaining adequate ventilation and filtration please refer to my prior post(s) on Indoor Air Quality

No Fireplace or Retrofit Wood-Burning Fireplaces.

Burning wood in fireplaces is a major source of sir pollution in the winter, generating up to one-third of outdoor air particulates on cold nights. In addition, conventional open fireplaces suck air out of the house and send more heat up the chimney than they provide to the room. In recent years, a number of cities and counties in California have enacted local ordinances that permit the installation of only gas-burning fireplaces or EPA certified wood-burning appliances.

For a current product list of EPA certified wood burning stoves click here.

Existing wood-burning fireplaces should be retrofitted with airtight doors and working dampers to reduce down-drafting, heat loss and the amount of air drawn from the house for combustion. An even better alternative is a gas insert with sealed combustion; these products have efficiency up to 85 percent, compared to typical fireplaces which are only about 13 percent efficient.

Retrofit conventional wood-burning fireplaces with EPA certified wood or pellet stoves. All units should have combustion air vented directly into them from the outside. For gas units, the listed efficiency should exceed 60 percent (only available using The Canadian Standards Association, CSA P.4.1-02, ‘Testing Method for Measuring Annual Fireplace Efficiency’ – EnerGuide Rating System).

Why has Canada developed its own fireplace efficiency rating?

Different methods have been used to measure the efficiency of gas fireplaces. Steady state (SS) and annual fuel utilization efficiency (AFUE) ratings are based on test methods originally created for wall heaters, space heaters and furnaces. The energy efficiency numbers generated by these test methods did not reflect the actual energy performance of gas fireplaces.

Working with industry, the Government of Canada set out to develop a new test method for gas fireplaces. The Canadian Standards Association (CSA) P.4.1-02 test method, introduced in 2003, was developed as a consensus standard (keep in mind, there is no such thing as a perfect standard). It mainly provides an ‘apples-to-apples’ comparison when appliances are operated in a realistic mode using a standardized test methodology. The CSA P.4.1-02 test method generates a fireplace efficiency rating (FE Rating), expressed as a percent efficiency – the higher the number, the more energy efficient the product.

If it is not feasible to totally retrofit the existing fireplace, then at least replace the old damper if it no longer seals the flue due to mechanical failure, rust or soot buildup in the chimney. Also retrofit fireplace with sealed doors and bring outside air for combustion from behind the doors.

EPA certified wood-burning stoves and CSA rated gas fireplaces reduce the amount of particulate pollutants by 75 – 90 percent compared to a standard fireplace. A properly operating damper reduces drafts in the house when the fireplace is not in use. Airtight doors can reduce the heat taken from the house as well as reduce drafts when the fireplace is not in use. Finally, efficient gas fireplaces consume less gas and save money compared to conventional gas fireplaces.

Install Efficient Exhaust Systems in Bathrooms and Kitchen.

Excessive moisture resulting from poor ventilation is one of the main causes of mold issues and building failures. Bathrooms and kitchens produce odors and a lot of moisture that can cause problems if the rooms are not properly ventilated. Gas ovens and gas cooktops produce carbon monoxide, nitrogen dioxide and other pollutants. Additionally, cooking food produces odors and particulates.

Install ENERGY STAR bathroom fans vented to the outside.

Exhaust all bathroom ventilation fans to the outdoors, not to the attic. Choose ENERGY STAR qualified bathroom fans; quieter fans will have a rating of 1.5 sones or less.

Put all bathroom fans on a timer or humidistat.

Bathroom fans should be controlled by a timer or humidistat to ensure proper run-time to adequately remove moisture from the room. Timers are triggered when the lights are turned on, and then run for a set time; 15 to 30 minutes usually works well. Humidistat controllers are even better, as they automatically switch on when moisture in the air reaches a threshold level, and shut down when the moisture level subsides.

Install kitchen range-hood exhaust system vented to the outside.

Use high efficiency range-hood exhaust systems that are ENERGY STAR qualified and vent them to the outside. ENERGY STAR units are typically designed to be quieter (less than four sones) so that people will be more likely to use them. Don’t buy overpowered hoods that may cause backdrafting of fireplaces and other combustion appliances.

Venting range hoods to the outside reduces the amount of moisture inside the home, and helps prevent adverse health effects from combustion gasses and cooking emissions.

For a current product list of ENERGY STAR qualified ventilation fans and range hoods click here.

Install Mechanical Ventilation System for Cooling.

Ceiling fans improve a home’s comfort by circulation air. ENERGY STAR qualified models are energy efficient thanks to improved motors, blade designs and fluorescent light kits; also, they can be operated to either draw warm air upward in the summer or push it downward in the winter.

Whole house are used instead of an air conditioner to cool a house at night. They exhaust warm indoor air and bring in large volumes of cool outdoor air.

Install ENERGY STAR ceiling fans and light kits in areas where occupants tend to spend more time, such as bedrooms and family rooms. Anchor ceiling fans to ceiling joists. For fans with built-in lights, select models with ENERGY STAR qualified compact fluorescent light fixtures. If the fan doesn’t include lighting, purchase an ENERGY STAR qualified light kit.

Install a whole house fan with variable speeds. A whole house fan is appropriate for single-story and multistory homes. In a multistory home it must be mounted in a hallway ceiling on the top floor. An insulated, airtight seal is necessary to prevent air leakage through the fan in winter. Fans should be sized to produce between four to five air changes per hour and should have two speeds: low speed for continuous ventilation and high speed. When the fan is running, you must keep a few downstairs windows open to allow the outdoor air in and avoid backdrafting of carbon monoxide from gas appliance flues.

Ceiling fans can make residents feel more comfortable while cutting back on their use of heating and air conditioning systems. ENERGY STAR qualified models provide greater energy savings thanks to improved blade and motor design and integrated compact fluorescent lighting.

An average whole house fan uses one-tenth the electricity of an air conditioner. Moving large volumes or air can achieve indoor comfort at higher temperatures without air conditioning.

For a current product list of ENERGY STAR qualified ceiling fans click here.

For a current list of ENERGY STAR ceiling fans with light kits click here.

For a list of ENERGY STAR ceiling fan light kits click here.

Install Mechanical Ventilation for Fresh Air.

An air-to-air heat exchanger (also called a heat or energy recovery ventilator) is a mechanical fresh air ventilation system that recovers heat from exhausted indoor air and transfers it to the incoming fresh air stream.

Install an air-to-air heat exchanger to deliver fresh air to high occupancy areas like bedrooms and living rooms. Use of this equipment is particularly appropriate if a blower door test of the home shows less than 0.35 Natural Air Changes per Hour (NACH).

Air-to-air heat exchanges introduce fresh air into the home while reducing energy loss by capturing heat from the exhausted air stream and transferring it to the incoming air.

Install Carbon Monoxide Alarms.

Carbon monoxide (CO) is emitted from fuel-burning appliances such as stoves, cooktops, water heaters, furnaces and fireplaces, as well as from cars and some landscape equipment. If a home is tightly built for energy efficiency but has leaky HVAC ducts, the air leaks may depressurize the home and reverse the flow of exhaust vent pipes. This can introduce carbon monoxide from fuel-burning appliances back in to the home, a process known as backdrafting.

Install a carbon monoxide alarm per manufacturer’s instructions. Alarms must comply with both UL 2034 and CSA 6.19 standards. Alarms must be replaced every three to five years, as they lose their sensitivity over time.

Additionally, a carbon monoxide alarm provides an added level of safety for homeowners and occupants.

They say a picture is worth 1,000 words, so before you leave be sure to visit Von Löwen Designs to view an assortment of refreshing examples in kitchen and bath design concepts, refined palette and interior finishes, and sustainable yet chic, green remodeling ideas that may encourage and inspire your next remodel or home improvement project.