Cavity Walls

Cavity walls are external building walls which incorporate an air gap which may be within the wall structure itself (for e.g. Hollow block walls) or between two solid walls (or between two partitions having a narrow air gap separating them).The latter technique was widely used in houses constructed between 1932 to 1982.

Almost all houses constructed after 1982 adopted the cavity wall technique with or without the use of insulation.

Why do you need insulation in cavity wall?

The wall cavity maintains an air gap which is a good insulation. (In fact it is about the best available conveniently and almost all other manufactured insulation material incorporates air bubbles or spaces in order to gain this advantage).When the cavity width between the two walls exceed a certain critical dimension the air within the gap start moving about due to convection (convection currents) which start assisting heat transfer from the warmer to the colder side rather than blocking it.

Porous insulation fill will restrict the air movement within the cavity providing optimized insulation quality.

How to find out whether your house has cavity walls

All houses built during the last 25 years are almost certain to have cavity walls. It is possible these may be insulated too. Houses built during the 50 years prior to that are also likely to have cavity walls but may not have any insulation.

A sure giveaway sign is the brick pattern of the exterior wall. In general wall bricks are laid in 3 patterns. viz;

Stretcher bond Flemish bond

And,

English bond

Of these only the stretcher bond patterned brick walls will have a wall cavity. A stretcher bond patterned brick wall will have the bricks laid flat on side and in a linear manner i.e. bricks laid end to end.

Another tell tale sign is the width of the total wall. Due to the incorporated cavity the width is in excess of the normal 300 mm width you would expect it to have.

It is always better to get a skilled person with proper tools to give advice on these matters. Normally they drill holes in the wall and collect data to find out the details of the air gap, insulation material (if any), and the present condition of it.

Types of insulation for cavity walls

The commonly used materials are;

Fibreglass or mineral wool with short strands Cellulose loose fill or stabilized cellulose Phenolic and other Synthetic foam cavity board ?(Used in new constructions only).

Cavity wall insulation if it is a retrofit in an existing house will not take more than 3 or 4 hours. Of course it has to be handled by a skilled person with specialized tools. They would drill holes in the existing external wall at regular intervals, insert a special nozzle and blow short strands of insulation material in to the wall cavity. If the house is being constructed anew phenolic foam rigid board or expanded polystyrene foam boards too may be used.

Wind power generation, an alternative and renewable energy source, has seen a dramatic increase in the last few years. Technological advances make it more and more feasible to install wind power generators for individual homes. The newer systems are more efficient and quieter.

Not every geographical location however, is suited for installing a wind power generator. A consistent wind, with average speeds of approximately 11 miles per hour is required to make a wind energy system feasible. Lower wind speeds can be suitable for battery charging and water pumping in your remote weekend cottage.

Wind availability maps are published by the US National Renewable Energy Lab. You can get a general idea from these maps if you are living in a state and county with sufficiently high winds.

Once you confirm this, you will need to also check if your exact location experiences the required, consistent average wind speeds. If your home, your property is located on the side of a hill, your sheltered location might not provide the required wind speeds. Maybe you can install the wind turbine high enough, to just extend it over the ridge. You will then possibly be able to pick up sufficient wind.

Local wind maps, can also be found at the National Renewable Energy Lab. These maps howver, are not very easy to read and understand. Fortunately though, you can simply contact a wind power manufacturer, such as those listed in the American Wind Energy Association website. They can tell you if it is feasible to install a wind power generator for your home.

At this point, just get some general information about the feasibility of installing a wind power system for your home. You have some more checking to do, before you spend a lot of your and the manufacturer’s time on details.

Next step is to check the local codes and requirements. Your town might have some bylaws, or if you live in a subdivision, there might be restrictions in place, that will not allow you to install a wind power generator for your home. Don’t let that deter you! Get a petition going in your town or city to change the bylaws.

Talk to the neighbor hood association. Who knows, maybe the whole subdivision will end up supporting a wind power generator for all the homes!

Don’t forget to also talk to your neighbors. Unfortunately, some people still believe that all wind energy generators are noisy and kill birds. Inform the neighbors as you investigate and learn more.

Once you know that no local laws, regulations, neighbors or neighbor hood associations will stop you, it is time to talk to the manufacturers again.

I recommend talking to at least two different wind power manufacturers with different types of rotors, such as horizontal propeller blades, or vertical ‘egg beater’ blades. Each of these has advantages and disadvantages. You want to make sure that the type of system you end up installing is the best for your particular application.

Ask the manufacturer a lot of questions, such as:

- How much clearance is required around the tower and rotor blades?

- How tall will the wind tower be?

- What are the noise emissions? Do they have certified sound data?

- How many installations have they done? Can you go see one?

- What output can you expect from their system?

- What is the installed cost per kilowatt-hour?

- What kind of warranties do they provide?

- What will they need from you to do to make it happen? (besides money)

- Will they apply for the required permits?

- Will they make the connection to the electric grid?

- Will you have to hire a general contractor?

Compare all the answers between the different models and manufacturers and then you can make an educated decision.

A handful of States provide some incentives for installing small wind power systems. Check with your state and local governments. Another option could be to get a reduced-rate mortgage for adding the wind power system. Check with your mortgage company or mortgage broker.

If you find after doing all this research, that wind power is not the solution for you, then maybe a solar photovoltaic system is your solution.

I do hope that you will be able to install either a solar energy system or a wind power generator for your home.

What are lighting alternatives to save energy?

The best form of energy efficient lighting is natural light which everyone has the access and right to consume and maximize. It mainly depends on the person’s initiative and discretion how to make use of natural light which is abundant everywhere all the time. Start with the basic structures and positions of windows and door openings in your home. You can install windows and doors to become passageways of natural light either in the northern or southern part of your house. North-facing windows are great sources of natural light without suffering the summer heat or winter cold that is likely to enter your interiors if windows are not properly installed. You can also use light colored interior designs and surfaces to reflect natural light and lessen the need of your room or interiors for artificial lighting.

Another way of saving energy through lighting your house is through using fluorescent lights. Fluorescent light is considered the most energy efficient type of light compared to its incandescent light counterpart. Although this alternative is much more expensive to buy, you are surely getting a great deal with energy consumption. It can consume only one quarter of energy which is likewise used by incandescent bulbs provided the same level of light.

Fluorescent lights, varying between linear and tubular kinds, are also more durable and can work for up to twenty thousand hours which is why it is ideal to use in living rooms and kitchen areas. This is also a good lighting option for security lighting purposes. It can produce lesser heat and keeps your interior cooler during the summer season consequently helping you save more on cooling system like air conditions.

How to use lights efficiently?

In order to save energy and use your home lighting more wisely, here are some ways you can do.

Use only the right wattage bulb you need in order to avoid excessive lighting of certain areas in your house. Always turn off unnecessary lights especially if you are not using them for more than 10 minutes. Decorate your rooms and interiors with light colored furnishings and finishes to require lesser artificial lighting and allowing natural light levels.

Finding the right kind of lighting for your home does not only involve using the right bulb and electrical or lighting alternatives. You also have the power to do something and make a great difference in your energy consumption. Using energy efficient lighting and doing the necessary steps for saving energy will surely benefit you and the environment as well.