Like other sustainability outcomes discussed in this series of articles, lifecycle costing needs to be considered throughout the project process to ensure the home you build meets your expectations.
1. Define your priorities and set objectives
Budgets for new house projects typically focus on the cost to build the home. In addition, objectives or principles can be discussed and agreed with the design team that incorporate the other aspects of lifecycle costing. For example:
- Targets may be set for operating costs for water and energy that guide selection of products and systems.
- A maintenance schedule and budget can be established at the beginning of the project and added to as products and systems are considered and selected.
- An expectation can be set as to the lifespan of the building that guides selection of products and impacts the maintenance schedule.
2. Prioritise and test design
- Cost to build will increase because more materials and time are required.
- Operating costs and heating costs in particular will increase as there will be a larger internal area to keep warm.
- Maintenance costs will increase as more materials used in construction results in more materials to be maintained over time, and more materials to be replaced at the end of their lifespan.
Cost savings through design
- Placing and orientating the building on the site to make the most of the sun’s energy for heating and local wind conditions for cross-ventilation. This can reduce or eliminate the need for heating and cooling systems and the energy to run them.
- Designing a roof of the right size and pitch to maximise the performance of PV solar panels. This will result in more energy generated, thereby reducing ongoing electricity costs.
- Designing a roof of the right size to capture the volume of rainwater required. This can maximise the contribution of rainwater tanks and reduce the cost of mains water supply.
3. Use systems and products to optimise design
- Building envelope. Investing in a better-performing building envelope through improved glazing and insulation can reduce or eliminate the need for heating and cooling systems and their associated maintenance and replacement over the life of your home.
- Operating costs of systems. Some of the systems in your home will deliver a reduction in one type of operating cost but an increase in another. For example, a rainwater system to reduce water costs may also require a pump that requires energy to operate. It is important to consider both when determining the impact on operating costs.
- Maintenance costs of systems. The performance of systems in your home will diminish over time if they are not properly maintained. It is also important to factor in the replacement cost of systems and their expected lifespan within your home.
- Fittings. The fittings you install will impact the supply of energy or water to your home. For example, using LED lights throughout your home can reduce the size of the PV system required to meet your energy targets. Fittings related to hot water use (e.g. showerheads) can reduce not only the amount of water supplied to the home, but also the amount of energy needed for water heating.
- Finishings. Some low-toxicity finishes such as paint or untreated timbers may result in higher maintenance costs due to more frequent reapplication or replacement. Many low-toxicity products are available that are just as durable as more toxic options and maintenance information should be sought from suppliers.
4. Build well
- Good construction will ensure your house performs as it was designed, especially in regard to thermal comfort. A house with acceptable levels of airtightness will retain heat whereas a draughty one will let it out quickly. If your house can’t keep the warmth in, your heating system will have to work harder to keep the house at comfortable temperatures, resulting in increased running costs over time.
- Periodic maintenance of your home will be necessary for systems and products to perform in the best way possible. If these are installed without following the manufacturer’s instructions they can deteriorate faster and will need to be replaced or serviced earlier than expected.
5. Use your home intelligently