Construction Science

Introduction.

An audit consists of a horizontal approach to all aspects of the use of energy and insulation, or that somehow contribute to the characterization of energy flows.

As such, energy audit can be defined as a detailed examination of the conditions of energy use in a facility. The audit allows to know where, when and how energy is used, what is the efficiency of equipment and where there are energy waste, also indicating solutions to deficiencies.

The energy audit aims to characterize the energy facility and installed systems, as well as identify and study measures technical and economic feasibility to introduce in order to reduce the energy consumption required for its activity. These measures will be incorporated into a strategic plan of action that clearly define the steps to take and the goals to be achieved with regard to reducing energy consumption.

The effective management of an Audit is a process that involves some tasks to develop, ranging from detailed analysis of energy consumption and patterns of isolation, through detailed analysis of the building, by physical analysis of the generating equipment and/or consumers energy, its operating conditions and control, as well as the care and maintenance of its operating time, until the final stage of the study which pointed out the results and measures to be taken to reduce energy consumption and heat loss.

Task 1.

No. 1 and 2

* External wall (cavity wall)  u = 1.6 W/m²K

Changing the type of brick from brickwork to lightweight concrete block (100mm thickness) and lightweight plasterboard (13mm thickness), decreasing the U-value to 0.58 W/m²K.

Furthermore, changing the clear cavity to insulation in cavity, which does not alter the thickness (50mm), the U-value decreases to 0.48 W/m²K.

* Wall construction  u = 0.63 W/m²K

Layer Thickness (m) Thermal conductivity (W/mK) Standard resistances (m²K/W)

External Fletton brick 0.103 0.077 0.134

Concrete block 0.115 0.11 1.045

Cement/sand 0.185 0.57 0.325

Plaster 0.015 0.18 0.083

RT = 1.587 m²K/W

u = 0.63 W/m²K

A regular wall is composed by internal surface, lightweight plaster, aerated concrete block, polyurethane insulation board, clear cavity, exposed brickwork and external surface, and have the U-value of 0.31 W/m²K.

* Solid floor  u = 6.67 W/m²K

The house has a solid floor with high emissivity, making a low thermal insulation. The insulation can improve lowering the emissivity of the floor, changing the U-value to 1.79 W/m²K or, been even more effective, making a suspended timber floor, changing the U-value to 0.25 W/m²K.

* Roof  u = 5.55 W/m²K

As the house was built in the 1960s, the roof is very old. Changing the tiles for younger ones, already improves the U-value to 4 W/m²K.

* Windows  u = 4.8 W/m²K

Changing to double glazing the U-value improves to 2.7 W/m²K and changing to triple glazing the U-value improves to 1.6 W/m²K.

* Central heating system:

HOW IT WORKS:

The cold water tank draws water from the cold water mains to refill. Then, the water from the tank goes down the cylinder. The central heating boiler will heat the cylinder; that way, it releases gallons of hot water. A pump circulates the hot water via the pipes and radiators spread all over the loft.

The benefits are: faster flow rates; multiple tap operation; backup electrical hot water heating; heating and hot water are together and it is solar compatible.

THE PROBLEM:

It requires a large space directed to the water tank in the loft; it will take time for the water to heat up; the amount of hot water is limited because it takes time to re-fill and heat; the energy generated is wasted as heat in the power station and along the grid.

HOW TO IMPROVE:

The regular boiler can be replaced by a boiler that generates efficient heating and hot water, as well as generating low-carbon electricity for a renewable energy supply. The advantages of this boiler are: it works in the same way as a conventional boiler; it generates electricity; it allows the loft owner's to benefit from the Government's Feed-in Tariff where he/she can be paid for electricity generated; payments through the Feed-in Tariff are guaranteed for 10 years. Inspite of being really good, the only problem is that it needs to be installed on the ground floor, and cannot be installed above kitchen units. The ideal place for the new boiler in