Value Engineering – Gas vs Electricity | C-Link

30 November 2018

Value Engineering – Gas vs Electricity

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M & E can be difficult to amend from a VE perspective as, in many cases, the scheme specified has been designed to comply with certain Planning Requirements such as BREEAM. The systems specified help the building to achieve a certain BREEAM score and therefore, it’s not simple to VE the package without compromising on performance to some extent.

However, we would always look at the products that have been specified and the warranties that are attached to them to identify VE opportunities.

So how and where can you Value Engineer M & E systems?

Centralised Plant and HIU’s

To ensure you retain the BREEAM Score required by planning, typically you need to adopt an add / omit approach.

One thing to focus on is the operation of plant in the building. For example, we worked on a project with 100 apartments where the specification included Centralised Plant and Heat Interface Units and we knew immediately that:

  1. The scheme was high-performing but expensive
  2. Even with Value Engineering, a high BREEAM score could be achieved

Heat Interface Units (HIU) are high performance products and they work in a similar way to a traditional Combi Boiler – i.e. they heat water directly from the mains when you turn on a tap, so there’s no need for a hot water storage cylinder or a cold-water storage tank in the roof space.

We looked firstly at the HIUs that were specified and compared them to HIUs that we’ve used on previous projects over the last 3 years. Switching the HIUs on this particular project would not only save £800 per unit (£800.00 x 100 = £80,000.00) but would also deliver the end user with an extended warranty of 4-years rather than 1-year.

Also, rather than each flat being independently heated directly by electricity or gas, the specification proposed to heat each flat via the flow and return water provide by a central plantroom. A centralised plant room has the benefit of reducing the environmental impact by reducing gas volume requirements and in turn, carbon emissions. This system is often chosen as a simple means of achieving a high BREEAM score, but it is expensive and there are more economical ways to deliver this.

We proposed a new solution to move away from Centralised Plant and Heat Interface Units to Hot Water Cylinders and Electric Panel Heating (not storage heating but electric convector heating).

This simple change delivers a major material saving: the unit price of a HIU is circa £2,500 whereas a Hot Water Cylinder and Electric convector heater is closer to £1,500k – where you have 100 apartments, that’s £100,000!

Also, if everything is being heated electrically as opposed to with gas, you negate the need for gas Centralised Plant which can bring further construction savings of around £200,000.00 depending on the size of the scheme.

The new system did have drawbacks; electric heating in lieu of gas had a negative impact on the BREEAM score and therefore, we had PV panels introduced to compensate. Nevertheless, we made a big saving as below:

  • Omission of Centralised Plant and HIU’s (saving £380,000)
  • Addition of Electric Panel Heating and PV Panels (add £80,000)

The BREEAM rating of the building was maintained together with a saving of £300,000!

Pipework Specification

In addition, if steel pipework is specified there are genuine chances to improve the budget and programme by moving to a pre-insulated plastic pipe which:

  1. Reduces programme
  2. Increases flexibility in design and site
  3. Reduces risk of leaks

Steel pipework is a high-quality product with a good environmental performance due its long-lasting qualities. But, it only comes in standard 6 metre sections meaning there are multiple joints and delivery costs are higher.

Joints brings multiple issues:

  1. Additional labour is required to install the joint on site and
  2. There’s an increased chance of defective installation that leads to leaks and remedial works.

As a result, it’s standard practice to install leak detection at each joint – again, increasing the material cost and the time to install.

Alternatively, Pre-Insulated Plastic Pipework is delivered in larger sections of up to 150 metres and it’s therefore possible to install hundreds of meters in hours as opposed to days. Because you only have two joints every 150 metres, you also reduce the need for Leak Detection and the risk of leaks full stop.

The saving in time and money can often be in the hundreds of thousands.

Steel pipework, is often specified for having greater life expectancy than plastic. In buildings where the mains runs at 80°c (typical temperature) steel has a life expectancy of 50 years versus 30 for plastic.

Plastic Pipework can achieve 50 years however, if the mains operates below 80°c. A flow temperature of 60-70°c would increase the life expectancy of the plastic pipework to 50 years and can be achieved by the specification changes above.

All of these changes requires a detailed analysis of the project specification, requirements and possible alternatives, but the savings can be substantial. On this project, we saved in the region of half a million pounds for ourselves and the client while concurrently retaining the BREEAM levels that Planning required – a success all round.

This piece was contributed by Sustinere UK. Sustinere UK aim to make energy efficiency and low carbon technology accessible, understandable and affordable. Visit Sustinere UK to find out more.

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