Balancing the options
With updates to the Building Regulations imminent, Peter Gammon, Technical Manager at MHS Boilers, reviews the major changes affecting the specification of heating and hot water systems in commercial buildings.
The task of controlling running costs in commercial buildings can be an on-going headache. For operators and facilities managers on the front line, there is a need to reduce energy usage. While for consultants, providing the most future-proof solution for a new building is vital.
As with any essential building service, heating and hot water systems are under the spotlight, not only to reduce energy usage, but also to limit the long term running costs of a building. There is a wealth of options to retrofit or specify, all of which can help achieve these objectives. However, before any one option can be chosen, the impending changes to the Building Regulations (due in April 2014) need to be considered.
A new raft of updates is set to have a significant impact on the specification of hot water products. The underlying intention of the revisions is to further minimise the energy use of buildings and, in terms of hot water delivery, optimise water heating systems and their capabilities to improve energy efficiencies. But, whereas the requirements of previous revisions were relatively low, the amended Regulations (Non-domestic Building Services Compliance Guide) are set to significantly tighten efficiency targets.
Although the last regulatory update affected the industry as a whole, the major change this year (certainly in the specification of domestic hot water systems) is the differentiation between new and existing buildings. In the 2010 edition, minimal thermal and boiler efficiencies were set across the industry, regardless of a building’s age. But April’s revisions will introduce a split between new and existing applications for certain types of system.
Bulk hot water delivery
For operators and facility managers looking to improve their hot water systems, the revisions will have less impact, with direct-fired, indirect fired and electrically heated options retaining the efficiencies from 2010. One method for bulk hot water delivery that has been a common retrofit is direct-fired instantaneous hot water generators. These deliver high volumes of domestic hot water and, when inclusive of an integral condensing circulator type heater, provide high efficiencies. However, there is a major note of caution when specifying these types of products: scaling. At typical hot water storage temperatures, if measures are not taken to condition the water, there is a high risk of scale fouling. Even a very thin layer of scale will cause a reduction in the unit’s performance, have a significant impact on lifetime efficiencies and could potentially lead to heat exchanger failure.
A practical alternative is to use indirect-fired water heaters, ideally with stainless steel heat exchangers which ensure high lifetime efficiencies. These units (such as the Thision WH from MHS Boilers) have a much reduced risk of scaling problems and can also boast a power to storage ratio which allows them to recover extremely quickly, delivering hot water on an almost instantaneous basis.
Such benefits have now made indirect units strong contenders for new build projects. This is bolstered by another major change to the Regulations, which sees a distinct split in efficiency targets for direct-fired units with an output above 30kW.
The change requires a minimum thermal efficiency of 90% (up from 73%), which will eliminate many direct type products currently available on the market. Indirect units, on the other hand, are not affected by the latest Regulations, with the current seasonal efficiencies remaining at 80%, 81% and 82% for natural gas, LPG and oil respectively. Consequently, indirect type products are an ideal option and, although their minimum efficiency requirement is less, they are typically able to perform to levels considerably higher than needed.
The amendments to the Building Regulations will also coincide with improvements to the non-domestic Renewable Heat Incentive, which were laid out in December 2013. Key features of the new policy worth considering for retrofitting and new-build applications are:
- An increase in support for renewable CHP, large biomass boilers (over 1MW), deep geothermal, ground source heat pumps, solar-thermal and biogas fuel
- New support introduced for air-water heat pumps
DECC is also planning an evolved approach to budget management. This will use improved market intelligence to allow credible growth rates across the range of renewable heating technologies supported, while also ensure the scheme remains affordable and achieves value for money. DECC estimates that the policy changes set out could incentivise around 5,000 non-domestic installations and an additional 6.4TWh of renewable heat by the end of 2015/16.
Taking advantage of the RHI and the opportunity to microgenerate energy has the potential to reduce running costs and greenhouse gas emissions. Bearing in mind the Government’s forecast for energy prices and bills (a 22% increase between 2013 and 2020, including the impact of energy and climate policies), integrating some form of renewable heat is becoming more imperative. This is especially true for medium-sized commercial premises, where the provision for essential heating and DHW services can account for up to 50% of energy demand.
Consider the regulations
Looking further into the future, specifiers of equipment should be encouraged to consider the regulations under the EU Directives 2015, which will be applied to the efficiencies of boilers and water heaters. One of the challenges that will affect the industry is the integration of high efficiency pumps.
The control of running costs has never played such a major part in both the daily running of a facility and specifying products for new builds. The heating and hot water industry will have to adapt to the demands of businesses’ needs in line with updated Regulations and
However, facilities managers and consultants should take careful note of the options, while considering alternative types of technology. This will help commercial premises incorporate long term effective systems that strike a balance between inflating fuel bills and energy efficiencies.