Passive ventilation

Passive ventilation

How does it work?

Passive ventilation uses doors, windows, vents, louvres and other openings to bring fresh air into your home and let stale air out. The size and placement of these openings can be used to guide air into and through your home.

Where cooling is required, windows or other openings on upper levels can be opened to let warm air escape. In winter, well-designed passive ventilation refreshes the air in your home without creating draughts or letting out too much heat.

Passive ventilation can only work if air has clear, uninterrupted pathways through your home. You can maximise air flow by designing open plan areas or having high vents or other openings between rooms. In general, windows should be larger on one side of the home than the other in order to encourage air flow.

If your home is designed for passive ventilation, all you'll need to do is open and close windows, doors or other vents as needed to reduce the temperature and improve the quality of the air you're breathing.

When should you think about ventilation?

When should you think about ventilation?

Planning a home or renovation

If you're building or renovating, ventilation should be considered early in the design process.

Good design should strike a balance between the need to introduce fresh, healthy air into your home and the need to maintain comfortable temperatures, so ventilation should be considered alongside passive heating and passive cooling options. If you consider heating without ventilation, you may end up with a home that's warm but not as healthy or comfortable to live in as it could be.

During and after construction

During the construction process and for a few weeks afterwards, you'll need to provide good ventilation to minimise your exposure to airborne pollutants such as formaldehyde from new building materials. See Unhealthy air for more.

In your existing home

In your existing home

Ventilation can be improved in an existing home without making significant alterations. Moving a door or window, or removing an internal wall might make a significant difference.

For ventilation to work as effectively as it should, your home should be well insulated. Then you can control your ventilation, rather than being draughty and cold.

Older homes tend to be less airtight than more modern homes. This can allow for some natural ventilation - but can also mean they're draughty and harder to heat. As a general rule of thumb, houses built before the 1960s will be very draughty, and houses built between the 1960s and 1980s will be quite draughty.  Modern construction, however, is much more airtight, meaning that problems with inadequate ventilation become more frequent.

Ventilation

Pic: Craig Robertson Photography for Beacon Pathway Ltd

With good ventilation, your home will be drier, healthier and more comfortable.

Ventilation is about helping air to circulate in your home. It allows moisture and airborne pollutants to escape, and fresh, clean air to be drawn into your home. Well-designed ventilation will provide cooling in summer. In winter, it will let stale air out but keep warmth in.

Effective ventilation depends to a significant extent on the size, placement and type of windows, doors and other openings in your home. With good design, you can control the circulation of air, rather than having draughts.

With good design, you can use windows, vents and other openings for most ventilation – this will save on your energy costs.  However, you may need some mechanical (active) ventilation, for example, extractor fans to expel moist air from the kitchen, bathroom and laundry outside.

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Does ventilation matter?

When should you think about ventilation?

Passive ventilation

Active ventilation

More information

Does ventilation matter?

Yes. A 2005 BRANZ survey of the condition of New Zealand homes found that many were damp and poorly ventilated.

Most bathrooms relied only on windows for ventilation. Only half of kitchens vented moist air to the outside. And 40% of timber-framed homes had poor or seriously inadequate subfloor ventilation.

Poor ventilation allows moisture and airborne pollutants to build up inside your home. This can cause health problems such as asthma for you and other members of your household. Moisture can also make your home uncomfortable to live in and damage its structure.

Ventilation

Pic: Craig Robertson Photography for Beacon Pathway Ltd

With good ventilation, your home will be drier, healthier and more comfortable.

Ventilation is about helping air to circulate in your home. It allows moisture and airborne pollutants to escape, and fresh, clean air to be drawn into your home. Well-designed ventilation will provide cooling in summer. In winter, it will let stale air out but keep warmth in.

Effective ventilation depends to a significant extent on the size, placement and type of windows, doors and other openings in your home. With good design, you can control the circulation of air, rather than having draughts.

With good design, you can use windows, vents and other openings for most ventilation – this will save on your energy costs.  However, you may need some mechanical (active) ventilation, for example, extractor fans to expel moist air from the kitchen, bathroom and laundry outside.

Geothermal Heat Pump System

Geothermal Heat Pump System 

Traditional heat pumps do the same thing as air conditioners but in winter, they do it in reverse, drawing their heat energy from the outside air. Geothermal heat pumps don't have to rely on the potentially wide temperature swings of outdoor air. They tap into the relatively consistent and more moderate temperatures of the earth instead. Using your yard, pond or well water, this ingenious technology enables you to enjoy higher energy efficiency inside your home—no matter how extreme the weather gets outside.

There are geothermal systems that can serve homes with ductwork or homes with radiant heat. The radiant heat versions are referred to as hydronic systems and some of those can also provide you with all your hot water needs.

A geothermal system can be used to provide all of your heating and cooling needs or you can pair it with a furnace for a dual fuel heating solution.

Packaged systems

Packaged systems

Some homes just don’t have space inside for a furnace or the coil needed for cooling. That doesn’t mean they can’t be filled with the same comfort and improved air quality of a split system home.

Packaged units tend to all look alike but can do vastly different things:

• Cool only as an air conditioner
• Cool and heat as an electric heat pump
• Cool and heat as a Hybrid Heat® dual fuel system of gas furnace with electric heat pump
• Cool and heat as a gas furnace with electric air conditioner

As an all-in-one unit, the only other thing you need is a control or thermostat and, of course, ductwork to carry the conditioned air. Additionally you can add air quality accessories if you like. Packaged systems may be located on the exterior of your home, either on a flat rooftop or in the yard.

Ductless split systems

Ductless split systems

As you may have guessed from its name, a ductless split system doesn’t rely on air ducts to spread treated air in your home. Instead, this specialty system is designed to heat or cool room additions or other places that may lack ductwork, such as home theatres, exercise rooms, garages or any other area where the existing system doesn’t quite cut it. Ductless split systems include:

• Small outdoor air conditioner or heat pump unit
• A compact indoor wall unit
• Refrigerant tubing and wire connections―pass through a small hole from indoor to outdoor unit to connect the system.
• On unit or remote control―your interface for controlling your system

Hybrid Heat® split systems

Hybrid Heat® split systems

It’s a smarter version of your standard split system, with an energy efficient twist: In addition to gas furnace heat, this system automatically figures out how to get the best efficiency by also using an electricity-fueled heat pump to provide warmth. Bonus―the heat pump functions in the place of an air conditioner too.

In the warmer, humid climates of the south you might consider a high performance heat pump with a lower efficiency and lower up front cost furnace so you can have the furnace as backup heating on really cold nights, while taking advantage of the high-efficiency heat pump most of the year. A heat pump with a variable-speed compressor matched to a furnace with a variable-speed blower motor can do an amazing job of pulling humidity out of the air in the summer to save money.

Meanwhile, in colder climates, it’s best to pair your heat pump with a high-efficiency furnace. Despite the cold, you might be surprised by just how much mileage―not to mention cost-saving efficiency―you’ll get from a heat pump in the spring, fall and, yes, even winter months.

A Hybrid Heat system includes:

• Heat pump―provides summer cooling and dehumidification and warmth in cooler seasons
• Evaporator coil―the indoor component of your outdoor heat pump
• Furnace―provides heating and the fan used year round to circulate air
• Ducts―carry the conditioned air throughout your home
• Control or thermostat―your interface for controlling your system
• Optional air quality accessories―clean, humidify, and freshen air before it circulates throughout your home

Systems that are at home in any home

Systems that are at home in any home

Your drapes, fabrics and paint colors were all chosen with care to suit your home and tastes. Your heating and cooling system should be just the same. That’s why we offer our innovative products in four configurations. One is sure to meet your needs perfectly.

Split systems

A split system simply means your solution has products that reside both inside and outside your home. In many cases, a split system consists of:

• Furnace―provides heating and the fan used year round to circulate air
• Evaporator coil―the indoor component of your outdoor cooling unit
• Air conditioner or heat pump―works in tandem with the evaporator coil
• Ducts―carry the conditioned air throughout your home
• Control or thermostat―your interface for controlling your system
• Optional air quality accessories―clean, humidify, and freshen air before it circulates throughout your home

Some split systems consist only of an outdoor unit―such as a heat pump or air conditioner―and an inside fan coil. If that’s the case, there’s usually another heat source in the home like baseboard heat or a boiler.

THE ABCS OF HVAC

THE ABCS OF HVAC

All you need to know about HVAC. Starting with what HVAC stands for.

It’s pretty easy to take the air you breathe for granted. But the fact is, there’s a lot to know about the heating and cooling systems in your home. And this is the place to start. (Especially if you want to take another thing for granted: Say, low energy bills.)

Air (ASHP)

Air (ASHP)[edit]

Main article: Air source heat pumps

• Air source heat pump (extracts heat from outside air)
  • Air–air heat pump (transfers heat to inside air)
  • Air–water heat pump (transfers heat to a heating circuit and a tank of domestic hot water)

Air-air heat pumps, that extract heat from outside air and transfer this heat to inside air, are the most common type of heat pumps and the cheapest. These are similar to air conditioners operating in reverse. Air-water heat pumps are otherwise similar to air-air heat pumps, but they transfer the extracted heat into a water heating circuit, floor heating being the most efficient, and they can also transfer heat into a domestic hot water tank for use in showers and hot water taps of the building. However, ground-water heat pumps are more efficient than air-water heat pumps, and therefore they are often the better choice for providing heat for the floor heating and domestic hot water systems.

Air source heat pumps are relatively easy and inexpensive to install and have therefore historically been the most widely used heat pump type. However, they suffer limitations due to their use of the outside air as a heat source. The higher temperature differential during periods of extreme cold leads to declining efficiency. In mild weather, COP may be around 4.0, while at temperatures below around 0°C (32°F) an air-source heat pump may still achieve a COP of 2.5. The average COP over seasonal variation is typically 2.5-2.8, with exceptional models able to exceed this in mild climates.

In areas where only fossil fuels are available (e.g. heating oil only; no natural gas pipes available) air source heat pumps could be used as an alternative, supplemental heat source to reduce a building's dependence on fossil fuel. Depending on fuel and electricity prices, using the heat pump for heating may be less expensive than using fossil fuel. A backup fossil-fuel, solar hot water or biomass heat source may still be required for the coldest days.^{[citation needed]}

The heating output of low temperature optimized heat pumps (and hence their energy efficiency) still declines dramatically as the temperature drops, but the threshold at which the decline starts is lower than conventional pumps, as shown in the following table (temperatures are approximate and may vary by manufacturer and model):

The Air Hygiene Log Book includes

The Air Hygiene Log Book includes:

• Site attendance register
• Works carried out & remedial actions log
• Annual task planner
• Lines of communication & responsibilities
• Training Records
• Safety data sheets & method statements
• Site visit reports
• Laboratory Reports
• Certificates of conformit

Types

Types[edit]

Compression vs. absorption[edit]

The two main types of heat pumps are compression and absorption. Compression heat pumps operate on mechanical energy (typically driven by electricity), while absorption heat pumps may also run on heat as an energy source (from electricity or burnable fuels).^[9] An absorption heat pump may be fueled by natural gas or LP gas, for example. While the gas utilization efficiency in such a device, which is the ratio of the energy supplied to the energy consumed, may average only 1.5, that is better than a natural gas or LP gas furnace, which can only approach 1.

Plumbing

Plumbing[edit]

In plumbing applications, a heat pump is sometimes used to heat or preheat water for swimming pools or domestic water heaters; the heat energy removed from an air-conditioned space may be recovered for water heating.

Applications

Applications[edit]

HVAC[edit]

In HVAC applications, a heat pump is typically a vapor-compression refrigeration device that includes a reversing valve and optimized heat exchangers so that the direction of heat flow (thermal energy movement) may be reversed. The reversing valve switches the direction of refrigerant through the cycle and therefore the heat pump may deliver either heating or cooling to a building. In cooler climates, the default setting of the reversing valve is heating. The default setting in warmer climates is cooling. Because the two heat exchangers, the condenser and evaporator, must swap functions, they are optimized to perform adequately in both modes. Therefore, the efficiency of a reversible heat pump is typically slightly less than two separately optimized machines.

Heat sources/sinks

Heat sources/sinks[edit]

A common source or sink for heat in smaller installations is the outside air, as used by an air-source heat pump. A fan is needed to improve heat exchange efficiency.

Larger installations handling more heat, or in tight physical spaces, often use water-source heat pumps. The heat is sourced or rejected in water flow, which can carry much larger amounts of heat through a given pipe or duct cross-section than air flow can carry. The water may be heated at a remote location by boilers, solar energy, or other means. Alternatively when needed, the water may be cooled by using a cooling tower, or discharged into a large body of water, such as a lake or stream.

Geothermal heat pumps or ground-source heat pumps use shallow underground heat exchangers as a heat source or sink, and water as the heat transport medium. This is possible because below ground level, the temperature is relatively constant across the seasons, and the earth can provide or absorb a large amount of heat. Ground source heat pumps work in the same way as air-source heat pumps, but exchange heat with the ground via water pumped through pipes in the ground. Ground source heat pumps are more simple and therefore more reliable than air source heat pumps as they do not need fan or defrosting systems and can be housed inside. Although a ground heat exchanger requires a higher initial capital cost, the annual running costs are lower, because well-designed ground source heat pump systems operate more efficiently.

Heat pump installations may be installed alongside an auxiliary conventional heat source such as electrical resistance heaters, or oil or gas combustion. The auxiliary source is installed to meet peak heating loads, or to provide a back-up system.

Heat transport

Heat transport[edit]

Heat is typically transported through engineered heating or cooling systems by using a flowing gas or liquid. Air is sometimes used, but quickly becomes impractical under many circumstances because it requires large ducts to transfer relatively small amounts of heat. In systems using refrigerant, this working fluid can also be used to transport heat a considerable distance, though this can become impractical because of increased risk of expensive refrigerant leakage. When large amounts of heat are to be transported, water is typically used, often supplemented with antifreeze, corrosion inhibitors, and other additives.

Reversible heat pumps[edit]

Reversible heat pumps work in either thermal direction to provide heating or cooling to the internal space. They employ a reversing valve to reverse the flow of refrigerant from the compressor through the condenser and evaporation coils.

• In heating mode, the outdoor coil is an evaporator, while the indoor is a condenser. The refrigerant flowing from the evaporator (outdoor coil) carries the thermal energy from outside air (or soil) indoors, after the fluid's temperature has been augmented by compressing it. The indoor coil then transfers thermal energy (including energy from the compression) to the indoor air, which is then moved around the inside of the building by an air handler. Alternatively, thermal energy is transferred to water, which is then used to heat the building via radiators or underfloor heating. The heated water may also be used for domestic hot water consumption. The refrigerant is then allowed to expand, cool, and absorb heat to reheat to the outdoor temperature in the outside evaporator, and the cycle repeats. This is a standard refrigeration cycle, save that the "cold" side of the refrigerator (the evaporator coil) is positioned so it is outdoors where the environment is colder.

• In cooling mode the cycle is similar, but the outdoor coil is now the condenser and the indoor coil (which reaches a lower temperature) is the evaporator. This is the familiar mode in which air conditioners operate.

heat pump

A heat pump is a device that provides heat energy from a source of heat or "heat sink" to a destination. Heat pumps are designed to move thermal energy opposite to the direction of spontaneous heat flow by absorbing heat from a cold space and releasing it to a warmer one. A heat pump uses some amount of external power to accomplish the work of transferring energy from the heat source to the heat sink.