Energy Audit

Erik Lund, Bakkelandets Energy Office.

The energy offices offer their members a general energy and resource audit of their home. The audit includes electricity, heat, and water consumption, plus recycling of household waste (separation, composting, etc.). It ends up with a report with directions on, how to lower consumption, and which savings can be obtained. This chapter goes briefly through the various elements of an energy audit.

Background

The energy audit roots in the family home, which is the smallest unit of society, but nevertheless a dominating energy consumer viewed as a whole. It is not only possible to save energy, but also to create a better indoor-climate, higher comfort, less building strain - and less strain on environment. The principles of an energy audit are useable for both existing and new buildings, and they should be adopted already in the planning phase to avoid investment mistakes.

Many circumstances play a part when energy consumption is examined: condition of the buildings, and their ability of keeping cold and moisture out, and accumulate heat inside; how the building is fitted out; size compared to number of occupiers; etc. Behaviours of the family play a role too, is everybody prepared to: keep doors shut, turn of the light when the room is not in use, turn off the oven so the after-heat can be used, etc.

An individual family can reduce energy consumption, but there will still be a need for energy supply, e.g. electricity. Therefore it is part of the energy audit to inform about possibilities to get the needed energy with as little environmental impact as possible, e.g. by establishing wind turbine cooperatives. Other elements taken into account are water saving, waste water treatment, and solid waste.

The Energy Audit

The energy audit is a general view based on the total energy consumption and production of a building, and behaviours of the users. The aim must be the smallest possible strain on environment.

When heat loss is reduced to a minimum, then the heat distribution is simplified at the same time, and it can be met by the ventilation system. The less energy consumption, the more dominant is free heat; solar incidence, body heat, and heat from electrical appliances. Therefore the great thing is to accumulate and distribute the free heat.

The building must be tight, as heat loss through joints can be significant. The necessary replacement of air can be provided by a ventilation plant, which transmits the heat from the outgoing air to the incoming air. By doing this, it is at the same time possible to keep an adequate low humidity. Dry air is easier to heat than humid air. The different elements influence each other.

Supply of energy is needed for domestic hot water, heating, light, household appliances, etc. Which source this energy comes from rely on the neighbourhood and local organizing. A local group can manage installation and operation of a wind turbine producing power, or a biogas plant which can produce both heat and power.

The domestic hot water consumption is nearly the same all year round. During the summer period the consumption can be provided by a solar heater. Autumn, winter and spring another heat source is needed for supplement. This can for example be a woodburning stove with integrated hot-water tank, where "waste" heat from water heating can be used for space heating, and distributed to the whole house by the ventilation system.

The following is a short description of the different parts of the energy audit.

Climate Protection, Heat Loss.

The starting point is a low heat loss from the building. This can be achieved by an efficient envelope, that at the outside protects against heat loss, and at the inside accumulates heat. The envelope must be wind tight, but at the same time so light that the cold is not accumulated. The heat loss increases with increasing wind speed, therefore a windbreak belt will also reduce the heat loss.

A greenhouse shelters the building and collects solar heat at the same time. It must be possible to bring me heat from the greenhouse into me house and/or accumulate it. Location of cold rooms in the prevailing wind direction can also protect against wind. Location of windows to the south (east or west) gives a supply from passive solar heating.

Energy Consumption

When we discuss energy consumption in relation to a home, the consumption from the following must be taken into account:

* production of building materials

* (re-)construction of the house

* maintenance of a comfortable indoor climate

* storage of food, and cooking

* lighting, radio, TV, and various hobbies

* cleaning

* domestic hot water

Each part must be evaluated on the criteria

* minimal environmental impact

* optimum use of materials

By construction and reconstruction, building materials and building methods with limited energy consumption are chosen. Insulation thickness is estimated from the total energy consumption (production and saving).

The house should be organized so that "waste" heat from cooking, laundry, etc., as far as possible becomes part of the heating.