The industry responds

The draft Regulations propose that U-values be progressively tightened. The delegates were asked whether this is an appropriate way to update the Regulations, and whether or not the insulation values should be tight from the start.

Delegates were also asked to consider whether the proposals for dealing with solar overheating are workable, and whether daylighting was adequately covered.

Ways to limit uncontrolled infiltration have entered the Regulations for the first time, but are the proposed airtightness standards and means of compliance both achievable and workable?

Delegates concurred with other groups on the unnecessary complexity of trading heating system efficiency against U-values. “If the U-values are so important at delivering real improvements in the first place,” summarised BRE’s Denice Jaunzens, “why introduce the complexity of trade-offs that won’t necessarily improve efficiency?”

There was also consensus that even a highly performing heating system would not be able to compensate for the shortcomings of low U-value elements, be they walls or windows.

Delegates agreed that it would be far better to make use of other mechanisms to improve heating system efficiency, such as “market transformation” techniques and the DETR’s Enhanced Capital Allowances mechanism (due to come into force in April 2001).

Delegates generally thought that the Carbon Performance Index was too lax. To set the pass mark for 2001 at the median value of the ECON 19 dataset – today’s typical level – would not achieve much, they said. Delegates considered that the upper ‘good practice’ quartile would be a more appropriate target.

The clauses covering overheating criteria for naturally ventilated buildings puzzled more than one delegate. Oscar Faber’s Ant Wilson queried if it was wise to set a limit of 28°C for ten days over ten years at a solar gain of 15 W/m2. “What weather data is that based on, and what datasets should designers be using in future given that climate change may affect our ability to meet the criteria?,” he queried.

“My reaction is that it will make people put air conditioning in their buildings, which is much easier than doing the calculation,” predicted Ove Arup’s Chris Twinn.

Delegates pointed out that the draft Regulations do not set a maximum space temperature for dwellings, which will become more of an issue with improvements in fabric insulation. Schools also tend to suffer from overheating, which will need to be addressed if they lose Crown exemption.

Airtightness

The discussion on airtightness threw up interesting views. BSRIA’s Andrew Eastwell said that the 75% improvement allowance on the standard – proposed by DETR to operate for the first 18 months the Regulations were in force – would simply encourage cheating. “The builder would just make it leaky to begin with,” he predicted.

Existing buildings are the biggest problem. I would like to see a programme to improve the energy performance of a house every time it changes hands

David Wood

Delegates generally agreed that the 75% clause should be deleted from the proposals. In the interim period, builders should just be allowed to get within 15% of the standard on retest. Once Part L has been in force for 18 months the pass mark of 10 m³/h/m² envelope would become effective.

Generally speaking, delegates supported the pass mark value. However there were rumblings that the inclusion of floor area in the calculation would enable a low, wide building to pass the test more easily than a tall, thin one.

Slough Estates’ Peter Thompson questioned the need for minimally serviced high-bay buildings – the crinkly sheds – to be covered by the airtightness requirements. “A lot of storage type buildings have very little energy input,” he argued, “so the environmental benefits from complying with an onerous airtightness value would be negligible. There needs to be some exceptions.”

BRECSU’s Vic Crisp pointed out the lack of good airtightness data for different building types. “Once industry gets used to the idea of pressure testing we should be developing standards for different types of building and forms of construction,” he said. There was a general view that different standards for different buildings could be set via the CIBSE’s forthcoming airtightness guide, TM23.

Design Flexibility

In this session delegates debated whether the Part L proposals will restrict design freedom. Is it right, they were asked, to allow trade-offs between fabric insulation values and heat system efficiency? If so, will the human and technical resources be available for the construction industry to self-certify its work? Moreover, can workable accreditation schemes be developed in time?

Delegates were split over whether it was sensible to trade-off heating system efficiency against fabric insulation. Some delegates argued that the thermal performance of the building fabric sets the inherent operational characteristics of a building, whereas long-term efficiency of a heating system is dependent on the proper operation of the building by the user.

“Given that the Carbon Performance Index allows designers to play with plant sizes and capacities, insulation values and hours of use, what is the point in having all these offsets with U-values?,” argued Arup’s Chris Twinn. “Why not just go for straight elemental values and minimum plant efficiencies?”

DETR’s Ted King pointed out that with the changes to the definition of material alteration, it will not be possible for a new building’s U-values to be traded- off against a high efficiency boiler, only to have that boiler replaced with a less efficient unit ten years on. The long-term proposals to bring existing building’s under the control of the Regulations should, he said, prevent that happening.

The proposal to permit wall U-values as low as 0.7 W/m²K took more of a hammering. While acknowledging that the performance of the whole building is more important than that of any one element the Summit delegates universally frowned on any slackening of fabric insulation values.

For a start it sends the wrong message. Second it’s not necessary for a builder to deliberately construct a sub-standard element. And third, they said, predicating such U-values on the long-term performance of systems and facilities management was a high-risk strategy.

While future editions of the Regulations may include the mandatory reporting of energy use, delegates considered that changes in building use may not allow the data to be accurately reported.

Surely Part L places a duty on us to educate clients to understand the need for flexibility in design

Paul Daly

“Surely [it places] a duty on us to educate clients to understand the need for flexibility in design,” said AMEC’s Paul Daly, “so that when the building churns 18 months after occupation it won’t affect the system operation to the degree that facilities managers have to change it,” he said.

System efficiency

Delegates were asked to question the proposed heating system efficiency standards. The proposed Carbon Performance Index aims to set performance standards for air conditioning and mechanical ventilation by combining envelope, sizing, system selection and control into a single measure of performance. Is this appropriate, or does it unfairly penalise any system?

On lighting, is the approach to defining lighting performance in terms of a luminaire efficacy rather than a lamp efficacy the correct way forward?

The DETR has chosen the median point in the Energy Consumption Guide 19 database for the Carbon Performance Index (CPI) pass mark in Part L. Many delegates thought this too low for new offices, though probably suitable for setting the standard for existing buildings.

“The median value in ECON 19 is for all buildings built since 1989,” reminded ESD’s Robert Cohen. “Can you imagine a new car today being built to the same quality as the average car already on the road?”

“We also have to think about other buildings, like schools,” added Cohen. “Design Note 17 may still be realistic for gas heating systems, but it’s already hopelessly out of date for electricity because of the amount of IT in schools.”

The clauses on covering specific fan power were welcomed, although concerns were raised over pressure drops through badly designed ductwork. Who would be responsible for checking compliances, asked delegates, and who would be responsible for putting it right?

Both Vent Axia’s Ian Andrews and Waterloo’s Jack MacFarland expressed concern at the manufacturing industry’s ability to get products on the market in time. “We need more information before we can say whether the standard should be 2 or 3 W/litre/s,” said MacFarland. “We also need to know what effect the fan power requirement will have on air handling unit design.”

Professor Max Fordham said that the tendency of products to degrade over time will be a problem for enforcing system efficiency standards. “It highlights the difficulty of doing things by government regulation when a pricing mechanism might get people thinking more about saving energy,” he said.

Again, delegates were very concerned at the thought of building control officers being given the responsibility for ensuring that energy efficient systems have been installed and correctly commissioned. There will be a vacuum, they said, in the expertise and resources of building control to ensure that the Regulations have been implemented.

“It occurs to me that the development of approved inspectors and a workable system of self-certification are essential prerequisites for the Part L proposals,” said the CIC chief executive, Graham Watts.

I think the Regulations should require 20% compact fluorescent lamps and leave the rest of the lighting design to the consultants

Owen Howlett

  “CIBSE, HVCA, BSRIA and the ECA can probably all develop competence schemes,” observed Oscar Faber’s Doug Oughton, “but the target date 2001 is very tight. It does not give the industry much time to get a sufficient number of competent persons in place.”

BSRIA’s Andrew Eastwell and CIBSE’s Richard John agreed. “CIBSE is very keen on developing competent persons registers,” said Richard John, “and we are watching [the performance of] pilot schemes to see how best we might do it.”

Lighting efficiency

On lighting, Ove Arup’s Bob Venning said the Regulations did not go far enough in encouraging the use of low energy systems.

“With the increasing efficiency of light sources it is already easy to meet 50 luminaire- lumens/circuit Watt, so the new standards don’t really offer much encouragement,” he said. “Perhaps [the Regulations] should contain minimum efficiencies for luminaire circuits [and a] prescriptive table of light sources and luminaire and lamp efficiency combinations to preclude those light sources which are out of date.”

Venning also proposed that the Regulations could call for lighting over ten years old to be replaced. “Many lighting installations were installed in the 1960s and they are not covered by the Regulations,” said Venning. “Perhaps they should be whipped out in ten years time as a legal requirement.”

Owen Howlett of Zumtobel was worried that the ability to trade-off high efficiency lighting against U-values might result in highly efficient but terrible luminaries which give poor lighting conditions. “I think the Regulations should require 20% compact fluorescent lamps, for example, and leave the rest of the lighting design to the consultants,” he said.

Commissioning and operations

Delegates were asked whether the Regulations should move beyond the assessment of building design and into performance in use. If so, how should the proposed logbook relate to existing documents such as operation and maintenance manuals, and health and safety plans?

The delegates were also asked to consider whether the proposed requirements for commissioning would change current practice, and whether the proposals for testing continuity of insulation and airtightness were appropriate and robust enough.

Delegates wrestled with Part L on commissioning and operation. How will the Regulations apply to leasing arrangements, or in multi-occupied buildings? Who will take final responsibility for building operation, and who will take responsibility for its carbon emissions?

Ove Arup’s Chris Twinn was quick to point out that the draft Regulations are expecting not just commissioning per se, but commissioning against the original design requirements.

Currently commissioning is done in accordance with the codes, which are not low energy codes. Daylighting control is a classic. You can put in the standard values for operating the lighting controls system, but you won’t end up with the lighting savings t

Chris Twinn

“The implication is that the designer, who usually has a historic understanding of the systems, now has to have input to make sure the systems are operating correctly,” he said.

“Currently commissioning is just done in accordance with the codes, which are not low energy codes,” he added. “Daylighting control is a classic. You can put in the standard values for operating the lighting controls system, but you won’t end up with the lighting savings that were intended.”

Slough Estates’ Peter Thompson said that consultants are unwilling or unable to write detailed commissioning specifications, “but it should be feasible to write specific requirements into the Regulations”.

This led to a debate on the virtue of the Regulations recommissioning of buildings, which DETR has proposed for a later stage.

Delegates considered that building MOTs could be an ideal way of covering operation of buildings. However, there were a lot of problems defining what the MOT would cover, what its purpose would be, how things would be measured, and what the implications are for those maintaining the building.

Arup’s Chris Twinn warned against expecting too much from a building MOT. It could just be a static check on a mechanical component, he said. “It won’t necessarily tell you what its energy consumption will be.”

Carrier’s Alan Tyson pointed out the problem of outsourced facilities management. “The maintenance of plant is a big issue. Facilities management companies tend to employ other companies to do the maintenance, so we need to identify the drivers to ensure that maintenance is done, done efficiently and to specification,” he stated.

AMEC’s Paul Daley agreed. “There are a number of difficulties in applying a MOT test to a building,” he said. “The efficiencies of building systems are a different issue from the way the operator is allowed to drive the building, which is more dependent on the type of building and the hours of occupancy,” he added.

Peter Thompson thought that building MOT’s carried serious implications. “When you start getting into MOT tests and issues of how buildings are operated, then the Regulations become more analogous to fire regulations and health and safety regulations” he said. “There is a question-mark over whether the Building Regulations are the appropriate vehicle.”

The key to this is clearly in the wording of the regulation. “The proposed Regulations are not necessarily in tune with current procurement contracts,” said BSRIA’s Chris Marsh.

“For these proposals to be effective they will have to recognise how responsibilities are divided between the parties to a contract.”

All opinions expressed at this summit were done on a personal basis and should not be taken to represent a corporate view.