Designing the perfect Passive House.

When people look to build a house to live in they have typical criteria such as

• Meeting the residential needs of themselves and their family

• Increasing their living space

• Moving nearer to work

• Moving near to immediate family

• Downsizing as the children leave home

There are numerous other reasons to build a home but when the decision to build is made the typical rationale is to

Buy a plot of land; get an architect to design the house and a contractor to build it. The process traditionally had four sectors working together

a. The client who pays for the services and building

b. The Architect who is head of the project

c. The Engineers who work with the architect and client on structural elements

d. The builder or contractor who builds the house.

Today the need to include energy design signals a new sector which involves all the traditional partners to work together to produce the Perfect passive design.

Architect

The role of the architect is pivotal in building a home.

People who build using existing house plans and then try incorporate the plans to fit their needs find the process ends in failure.

Engaging an architect to meet planning permission and house design but not employing him throughout the project cycle is shortsightedness and penny pinching.

Architects may sound expensive may be expensive but a good architect will add more value to your home and in the end the fee paid is tiny as a percentage of the overall cost of the house.

When choosing an architect the following information should be discussed and agreed before you award the brief

The cost should be discussed at the start and the amount of money to be paid agreed.

Architects are highly trained professionals and their time is expensive so agreeing a fixed price is preferable with allowances for additional inputs if required.

What the fee is for should be understood by you and what it includes and excludes.

Architects will design the house but not the structural elements so don’t expect them to.

If the architect engages other consultants on your behalf make sure the extent of their brief is fully understood by you.

Finally leave a contingency for unseen design events in the course of the building process.

Discuss in detail what you require from your house. It is amazing to note that people build homes and find later that they do not meet all their needs.

You need to look at your present situation allow for the future and ensure your house has special requirements build in if needed.

Architects will design and meet all your requirements and expectations so don’t impose restrictions on them.

If you restrict them too much you may get a draughting service only.

Finally let the architect know your building budget so he can design accordingly.

Engineers

Structural and service engineers are very important in the house design.

Whereas service engineers are not usually used in house design they may be useful in some circumstances.

Structural engineers are used to design foundations and other structural elements such as roofing beams etc.

In passive housing the need to eliminate cold bridging and to substantially increase insulation values require engineers to design differently than normal practice.

For example a traditional cavity wall with a 100mm cavity using steel wall ties was a tried and tested way to build.

A passive house requires the cavity to be 300mm wide and the wall ties to be of a low conductivity so the engineer must ensure that walls with this type of construction are designed carefully.

Another example is the use of cavity closers at the top of a cavity wall is unacceptable in passive houses.

The cavity insulation must meet the attic or roof insulation and eliminate the thermal bridge so the walls are not closed.

Designing the roof sitting on the inner leaf needs careful consideration and the need for additional strapping.

Finally passive foundations are sometimes poured on top of insulation which requires careful design to ensure that the housing load will not cause settlement.

Builders or Contractors

Building a passive house is not easy.

If it was we would be building them for a long time.

Builders make all the designs a reality.

In doing so they need to be fully aware of the principles of the design and the technical details

The builder must be able to discuss with the architect and engineer the merits or otherwise of each facet of the building process offer improvements and suggestions and pointout defects.

The role of the builder is to ensure the architects design is achieved and to be able to measure the efficiency of the passive building.

This is normally carried out by air testing and thermal imaging.

The Energy Efficiency design is carried out by either the architect engineer or the building contractor or others but all parties must not only understand the process but mustcontribute to it.

Client

The Client must engage fully with the process.

The house will be build for their needs and a hands on approach at the start will lessen the headaches later.

When plans are drawn up they should be studied in detail and questioned.

In that way clients get ownership of the house at an early stage.

It also will prevent redesign during the building process resulting in better budget control and avoidance of cost overruns.

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