Air Energy Recovery
What is Air Energy Recovery?
Heat Recovery Ventilation
Buildings, like people, need to breathe by taking in air and exhaling the waste in order that they remain fresh and habitable. The problem with traditional methods of ventilation, especially in winter, is that the outside air is usually colder than the air inside, and can prove costly to heat. A whole house heat recovery ventilation system extracts stale, moist warm air from a home through a heat exchanger. The system then supplies fresh air to the rooms through the same heat exchanger with up to 90% of the heat being retained. This means that the house benefits from a constant supply of heated fresh air without the need to open windows or incur significantly increased heating costs.
Types of Heat Recovery Ventilation
The two main types of heat recovery ventilation systems that are installed by the Green Energy Doctor are:
Whole House System
A whole house heat recovery system uses a heat exchange unit that is centrally mounted, usually in the loft or a cupboard and is connected to a well-insulated ducting system that extracts and replaces air through discrete ceiling vents in each room. The system extracts air from the kitchen, bathrooms and utility room through a heat exchanger and then supplies fresh air to the bedrooms and living rooms through the same heat exchanger with 90% of the heat being transferred.
Single Room Units
Single room heat recovery units work on the same principles as the whole house systems in that the stale air in the room is extracted through a heat exchanger and fresh air brought into the room through the same heat exchanger. The single room systems are designed to circulate air in single rooms, especially rooms with condensation problems or for the bedrooms of allergy sufferers. They can be easily fitted to any room that has an outside wall.
How Does it Work?
There are different types of heat recovery ventilation systems, but the principle on which they operate is similar. All Green Energy Doctor whole house systems consist of three main components:
Fan Unit with Heat Exchanger
The air is extracted from specific rooms (specifically, kitchens, bathrooms and cloakrooms) using an efficient fan that is housed in the centrally mounted unit. As the air passes through the unit, the heat is transferred to incoming outside fresh air that has been filtered to prevent the ingress of airborne pollutants such as pollen and dust. The system works by enabling the two air streams (in and out) to move close to one another without actually mixing. In this way, one air stream warms the other. This is done inside a counter- flow heat exchanger, which is made up of hundreds of individual air channels. This means that there is a large heat exchange surface area and hence the high efficiencies. The incoming flow is then introduced as warmed fresh air into habitable rooms such as bedrooms and living rooms. For a single room unit the air comes back into the same room.
Ducting
The main unit is connected to each room via a number of flexible or rigid ducting tubes that allow air to be drawn from and delivered to the specific rooms. These ducts can be hidden within internal walls and ceilings of the property. This is a very simple process for new build or existing properties of one floor, but may take a little more work for existing properties with more than one level.
Room Vents
Each room within the property that is to be ventilated will have a discrete circular vent either in the wall or the ceiling where the stale air can be extracted and the fresh warm air introduced.
Why is ventilation important?
There is increasing demand to make homes more energy efficient to reduce both heating costs and carbon emissions. Better insulation measures are good at achieving this, but also prevent air escaping from your home, like a sealed box. Without adequate and filtered ventilation, your home might be at risk from the following:
Dust Mites
High relative humidity allows house dust mites to thrive. A growing body of medical research indicates that the mite's droppings contain high levels of allergens, which are contributory causes of asthma and other bronchial reactions in susceptible individuals.
Pollen
Each year millions of people suffer from sneezing, coughing, itching, runny noses, and watering eyes when pollen is released from trees and plants. These tiny particles ride on air currents and can trigger the allergic reaction that many people know as hay fever.
Dust
Dust creates lots of problems, from eye irritation to lingering colds and allergies to a itchy or runny nose. More importantly, it makes a house dirty and that attracts more dust. As our homes become more airtight and 'electronic', the dust problem is worsened.
Pollution
Household cleaning agents, personal care products and solvents that make our lives so easy are also sources of hundreds of potentially harmful chemicals that contribute to indoor air pollution is wide reaching and diverse. Some of these products release contaminants into the air right away; others do so gradually, over a period of time.
Smells
One of the first things visitors notice when entering your home is its smell. With windows shut tightly during winter, household odours cannot escape, leaving air stale and sometimes offensive smelling. Cooking odours are one of the main culprits along with other lingering smells such as refrigerators, bins, pets, musty drawers and even shoes.
Condensation
Due to the relatively high levels of moisture vapour production from regular household activities, condensation can form very easily. Condensation often leads to mould growth, which damages the internal decoration and attacks the fabric of the building itself.
What Are The Benefits?
Eradicates Condensation and Its Consequences
The average household produces large amount of moisture vapour from regular activities such as breathing, bathing, clothes drying and cooking. In relatively well-insulated and sealed properties, this moisture can form into condensation if not properly ventilated. Condensation often leads to mould growth, which damages the internal decoration and attacks the fabric of the building itself. The system removes this damp stale air resulting in clean air without cooling the room down or incurring significantly increased heating costs.
Removes Health Risk To The Family
There is a growing body of medical research that shows that the pandemic of asthma in the UK is related to a lowering of whole house ventilation rates. Many homes are sealing their properties up, without ventilating them properly. This can create increased relative humidity that allows mould and the house dust mite to thrive, which are contributory causes of asthma and other bronchial conditions. A lack of ventilation can also cause the build-up of potentially toxic gases from burning fuel and synthetic materials in furniture and carpets, paints or cleaning products. Heat recovery ventilation has clinically proven health benefits by removing moisture and diluting indoor pollutants without cooling the property or incurring increased heating costs. Furthermore, the filters of the system help remove pollen that will benefit hay fever sufferers.
Energy Efficiency
Although the system uses a fan to drive the air, it is an extremely efficient motor that means the system still deliver energy positive ventilation compared to non-heat recovery methods. The heat exchanger is effectively collecting heat from the air leaving the building and reusing the energy to heat the incoming fresh air. This means that the energy that would otherwise be lost is used to heat the incoming air, helping to maintain a comfortable temperature.
Reduce Your Energy Bills
For those who do ventilate their property sufficiently, it is estimated that on average, 20% of the energy delivered to buildings is lost through departing ventilation air streams. In more modern buildings, the proportion of airborne energy loss can be even greater: up to 30%, due to the higher standards of thermal insulation. Extract ventilation systems can account for a significant proportion of overall building heat loss. Installing a heat recovery ventilation system could help reduce your energy costs.
Keeps Air Smelling Fresh
A whole house system would circulate and replace the entire volume of air of an average three-bedroom house approximately every 2 hours. Therefore, not only will it provide healthy clean air without you having to increase your heating costs, it will remove air that might contain unpleasant odours from pets, cooking or tobacco smoke to leave your home warm and smelling fresh.
Comfort
The system also eliminates the need for noisy bathroom extractor fans, window trickle vents or open windows. Therefore you can relax in a clean draught-free environment.
Security
By not having to open any windows, but still have a fresh environment you can constantly lock your windows meaning that your security will be improved.
How Much Does It Cost?
Whole House System
The typical cost for a professionally designed and installed heat recovery ventilation system for a two bedroom house is under �2,000 and for a large four bedroom house �3,000, depending on the complexity of the ducting work.
Single Room Systems
The typical cost for a single room heat recovery unit to be installed would cost approximately �600.
Once a technical survey has been carried out, all Green Energy Doctor prices will be given as fixed prices.
How to Get Started...
To organise a no obligation site visit or to start moving your project forward contact the Green Energy Doctor today on:
T: 0845 009 5652
E: info@greenenergydoctor.co.uk