Challenges of windy sites

Challenges of windy sites

Slowing down or excluding strong hot summer winds can be a challenge.

In some cases, the prevailing hot summer wind, sun and views are all orientated north.

It is important to know your site's climate and microclimate when you are planning a new home or renovation, so that wind direction can be considered. See Understanding your site and Orientationfor more.

On windy sites, consider:

• putting doorways and some windows into sheltered recesses so they can be opened even when it's windy to let warm air out
• using windows and doors on the south and east side of your home to provide for air movement without gusts if the prevailing wind is from the north
• using sliding windows - they won't slam shut in the wind
• using small openings - one at ground level and one in the roof or on an upper level - to provide for ventilation on windy days
• using wind breaks and mounded plantings around your home to slow the wind down and change the wind path.

Cooling air with water

Cooling air with water

When water evaporates, it absorbs heat from surrounding air, so the air cools.

Evaporation works best when humidity is lower so the air can take up more water vapour.

Rates of evaporation are increased by air movement and the exposed surface area of water. Fountains and mist sprays are effective for cooling.

Other options include pools, ponds and water features immediately outside windows or in courtyards to cool air before it enters the house.

Ventilation

Ventilation

Air movement keeps you cool by increasing the rate at which moisture evaporates from your skin. You'll need more air movement as humidity increases.

You can harness air movement by:

• orienting your home to catch the prevailing breeze
• using passive ventilation to get air circulating through your home
• combining passive ventilation with ceiling fans to direct the incoming cooler air where you need it.

Passive ventilation uses doors, windows, vents, louvres and other openings to let fresh air into and through your home. This helps to provide cooling, as well as removing moisture and airborne pollutants.

Leave your windows open to let breezes through your house.

See Ventilation and Orientation for more.

Options for ventilation

Options for ventilation

Ideally the air in a home should be 'renewed' every two hours, even when you are not at home. Some simple options are to fit aluminium windows with passive air vents or to fit security stays that allow the windows to be left ajar. When windows and doors cannot be left open, consider mechanical ventilation systems and air conditioning systems:

• Positive pressure or forced air ventilation systems work by blowing drier air into your house from the roof space above the ceiling or, in some types, from outside. They suit older houses with wooden joinery better than modern houses with sealed aluminium joinery – unless windows are opened or additional vents fitted.
• Balanced pressure / heat exchanger ventilation systems extract warm damp air from living spaces and pass it through a heat-exchanger to heat up dry air which the system brings in from outside. This can fully meet Building Code requirements. They work best in more airtight, modern homes.
• Extractor fans are used in places like the kitchen and bathrooms to remove steam.

For more information about ventilation systems go to consumer.org.nz. Note: you need to be a member to access this information.

Which system is best?

Thermal mass

Thermal mass

Materials with high thermal mass (materials that are good at absorbing and storing heat) can be used to aid heating in winter and cooling in summer. These materials are usually heavy - such as concrete and brick - and are used in floors or walls.

Used properly - the right amount in the right place, with proper insulation - will ensure they help passive cooling by absorbing heat from the surrounding air. They will keep absorbing heat as long as the air temperature is higher than the temperature of the thermal mass.

Thermal mass designed to get direct sun in winter, but not in summer, will stay cool during summer days and keep air temperatures down.

See Using thermal mass for heating and cooling for more information.

drive energy

By adding a small amount of drive energy, a heat pump can move heat from a low temperature to a high temperature. This means that the same piece of equipment can be used to remove heat from a space (cooling) at one end while at the same time adding heat to another space (heating).
The most prevalent use of heat pumps is for cooling, e.g. the common household refrigerator or air conditioner, but increasingly heat pumps are also used to upgrade heat to useful heating temperatures. In applications when both heating and cooling are needed this is a win-win situation which virtually doubles the cost-effectiveness of the installation.
According to the International Energy Agency, IEA, the buildings sector needs to reduce its CO2 emissions by over 70 % in comparison with 2010 levels in order to limit the increase in global temperature. The challenge is to achieve this reduction while at the same time energy demand is rising from an increasing number of both residential and commercial buildings. This challenge can be met by the heat pump technology, employing it in a wide range of applications in terms of heating, cooling and air conditioning.  Heat pumps are also a suitable solution for retrofit buildings. Therefore, heat pumps have a large potential in contributing to the reduction of global CO2 emissions.

Why heat pumps are a technology for the future

Sustainable energy systems of the future will rely on two major principles: efficient end-use and efficient use of renewables. In this scenario, the heat pump is a brilliant invention which is beautifully adaptable for a multitude of applications relating to both efficient end-use and renewably supply. The energy source used by a heat pump is renewable energy from ground, air, water and waste heat sources.

HPP Activities

 

 The primary activities within the Heat Pump Programme are, besides the Annexes, the triennial International energy Agency's Heat Pump Conference and the workshops which is held in conjunction with the conference. At the conference the Rittinger award is also handed out since 2005, the award is the highest international award in the air conditioning, heat pump and refrigeration field.

Earth heat

Some confusion exists with regard to the terminology of heat pumps and the use of the term "geothermal". "Geothermal" derives from the Greek and means "Earth heat" - which geologists and many laymen understand as describing hot rocks, volcanic activity or heat derived from deep within the earth. Though some confusion arises when the term "geothermal" is also used to apply to temperatures within the first 100 metres of the surface, this is "Earth heat" all the same, though it is largely influenced by stored energy from the sun.

What condition is your air conditioner in?

What condition is your air conditioner in?

If there’s an exception to the old “if it ain’t broke, don’t fix it” rule, it has to do with air conditioners. The EPA recommends you consider replacement of your air conditioner if it’s over 10 years old.1 If you want to get on board with doing the right thing for the planet and your pocketbook it makes sense because newer ACs are just that much more efficient than they used to be. For example, if you were to replace an old air conditioner with a 10-SEER rating with a new 21-SEER unit and proper indoor coil, you could save up to 56% on your cooling costs. Of course, there are other reasons why you might feel the need to pull the plug on your current unit right now:

• Your air conditioner needs frequent repairs and your energy bills are going up—your cooling equipment may have become less efficient
• Your cooling system is noisy—newer, variable-speed and even 2-stage systems tend to operate quieter.

Controlling moisture build-up

Controlling moisture build-up

Moisture accumulates in the house from people bathing, showering, cooking, breathing, and watering plants. It also comes into a home from outside. Some appliances, such as unvented gas heating, clothes dryers, dishwashers and washing machines also produce excess moisture into the air.

The moisture builds up quickly and is worse in modern homes which are built to be almost airtight. On cold days you can see the moisture when it collects on the windows as condensation. It is also absorbed into fabrics and building materials. The problem with this moisture build-up is that it can cause mould and mildew on walls and fabrics, which is not only unsightly, but can trigger allergies. For example, dust mites - the source of one of the most powerful biological allergens - thrive in damp conditions.

If you are building a new house, there are a number of chemicals and resins present in many building materials which continue to leak into the indoor atmosphere for many months after you move in. This can be managed with good ventilation.

The options for managing moisture are:

• Good ventilation.
• Window joinery with built-in drains - that allow condensation to drain to the outside.
• Keeping the house warm and dry through heating.
• Extraction fans in bathrooms and kitchens.
• Good insulation to keep the home warm and reduce condensation and mould growth.

Matching your system for optimum efficiency.

Matching your system for optimum efficiency.

Additional factors that affect the efficiency of your air conditioner or heat pump system are your indoor coil and blower motor. If your indoor coil isn’t properly sized to match your outdoor condensing unit, the system may not give you the stated SEER and/or HSPF ratings and could even develop performance problems. Not having a variable-speed blower motor means the system will tend to consume more electricity. That’s because the fan will frequently be operating a higher speeds than necessary to move the conditioned air in the house.

When you replace an existing outdoor unit, make sure you talk to your Carrier Expert about the potential effects of the indoor system on efficiency. It may be wise to replace both units in order to assure longer system life and gain peak performance, efficiency and comfort.

Cost savings

Cost savings

All your life, you’ve heard that you get what you pay for, and energy efficiency is no exception. The higher the efficiency of a heat pump, air conditioner or furnace, the more sophisticated the unit, and therefore, the more it tends to cost.

But despite the higher price tag, energy-efficient units invariably come with lower utility bills. Significantly lower, in many cases. As a result, you could see your additional investment paid back in only a few short years. And long after you’ve broken even with savings, you’ll continue to save on your energy bills―plus you get to enjoy the added comfort benefits that usually come with the model’s increased functionality.

How long would it take for one of our fuel-efficient systems to pay off for you? Your local Carrier expert would be happy to break down all the numbers for you.

OTHER BENEFITS OF CLEAN DUCTS

OTHER BENEFITS OF CLEAN DUCTS

Besides the obvious health benefits derived from cleaning HVAC systems, here are some other benefits:

1. Increased employee productivity - healthier people make better workers and lose less time to sickness.
2. Reduced housekeeping costs - the HVAC system is not pumping dirty air into the occupied space.
3. Increased airflow - because air moves unobstructed by debris build up, blowers and fans do not need to cycle as long or as often.
4. Energy savings - because motors and drives do not work as hard, less energy is consumed by the system.

DOING THE JOB

DOING THE JOB

Before beginning any duct cleaning job, the HVAC system must be shut off and locked out using approved lockout/tagout procedures. Drop cloths should again be used to protect the occupied space. The return side of the system is always cleaned first. The return side can typically be 5 to 10 times as dirty as the supply side.

Starting at the return air and outdoor air intakes, sections of duct are cleaned moving toward the main air handler. Sections of ductwork can be isolated for cleaning by inserting inflatable bladders in the duct and inflating them to block the duct off. Cleaned sections can be isolated in this way to prevent recontamination. An access opening should be made in the duct if one does not currently exist. Another opening is needed further downstream for connection of the HEPA filter equipped negative air machine. Typically, the distance between openings is 25 feet or less. With the negative air unit running, the cleaning tool is inserted into the duct and fed in the direction of the airstream. Some of the rotary brush type cleaners available can be fitted with a fan-like brushing tool that actually blows the debris toward the vacuum source. Care must be exercised when using a rotary brush in lined duct not to allow the brush to remain in one spot for too long. Close attention should be paid to cleaning fire dampers and turning vanes as greater deposits are often found in these areas.

Once the return side has been completed, the supply side of the system is cleaned using the same techniques. Access openings should be closed with reusable doors or air tight patches as the work moves along. Any disturbed insulation must be repaired as well. Grills and registers can be removed and pressure washed or vacuumed with the portable HEPA vacuum.

Particular attention should also be given to heating and cooling coils and drip pans. These are prime breeding grounds for microbial contamination and, if left uncleaned, will recontaminate the newly cleaned ducts. Coils and drip pans are best cleaned using the portable pressure washer and portable HEPA vacuum. At this time, drip pans should be checked for proper drainage and drainage systems freed of any obstructions.

Once the cleaning is completed and all access points resealed, a final inspection should be performed. Once the system is started up, it should be allowed to run until 8 complete air changes have occurred before the area is reoccupied.

Also, consideration should be given to the installation of more efficient filters on the HVAC system to reduce future contamination

SYSTEM INSPECTION

SYSTEM INSPECTION

Before cleaning is performed, the duct system must be inspected to identify any access problems or any damaged or contaminated porous materials which will require replacement. General structural condition of the system can also be assessed at this time. All inspection activities should be performed when the inspection area is unoccupied and the HVAC system is shut off. Use drop cloths to protect furnishings in the occupied space.

SAFETY EQUIPMENT

SAFETY EQUIPMENT

Safety equipment includes scaffolds and work platforms (working from ladders can be dangerous), lockout/tagout equipment, eye protection, breathing protection and cut resistant gloves.

PLANNING THE JOB

The first thing needed to plan a duct cleaning job is accurate mechanical drawings of the duct system. This is used as both a planning tool and a road map during the actual job. They make it possible to identify coils, turning vanes, access points and other important information. Duct cleaning is generally performed in sections of about 25 feet or less. These "cleaning zones" should be identified on the drawings when planning the job. Uncleanable types of duct should also be identified at this time and plans for removal and replacement made. Most flexible duct and certain lined duct work cannot be cleaned without damaging the ducting.

A cleaning schedule must also be established to ensure that all duct cleaning is performed in unoccupied areas.

PRESSURE WASHERS

PRESSURE WASHERS

It is helpful to have a small portable pressure washer that generates 500 PSI on hand. This unit is used to clean the coils and drip pans in the system.

ACCESS AND PATCHING TOOLS

Access openings are made using tin snips, hole cutters or other devices. When finished, access openings can be patched using reusable doors or with sheet metal, screws, duct tape, and sealant

AGITATION DEVICES

AGITATION DEVICES

There are three basic accepted agitation devices available for disturbing contaminants and sending them into the airstream created by the negative air machine. First, there is manual agitation by means of contact vacuuming. This method requires physical access to all surfaces either by reaching through access openings or physically entering the duct system. Next, there are a variety of air nozzles used to blow the contaminants off the duct surfaces. They require the purchase of a portable air compressor in addition to other equipment. Because they do not make contact with 100% of the inner surfaces, there can be doubts as to whether all surfaces were cleaned. The third agitation device in use is the rotary brush device. These consist of a brush or other cleaning device spinning on the end of a motor driven shaft. In most cases, a flexible shaft is used for ease of operation and to accommodate turns in the ducts themselves. Many duct cleaning jobs require the use of more than one technique.

Mercury

Exposure to mercury can damage the nervous system, causing problems with thinking, memory, mood, motor skills and more. Exposure can come from breaking a mercury-containing household product. But a more toxic form, methylmercury, gets into our food chain through burning coal, manufacturing products and improper disposal of products containing mercury

Toxic

When you're ready to buy new home furnishing and carpets, there are choices you can make to avoid bringing toxic chemicals into your home. There are also signs of wear to watch out for in existing products or when you buy second-hand