Luigi Schibuola

Performance analysis of heating plants equipped with condensing boilers

Abstract The behaviour of the condensing boilers is strictly bound to the temperatures of the water coming back from the plant. This temperature depends on the control modes and on the meteorological conditions. The seasonal performance has been computed for a heating plant of a building equipped with a condensing boiler simulating the load at short time intervals through a suitable modification of TRNSYS. The study has been carried out in the climate of Padova. For other towns a rough estimate is proposed.

High-efficiency recovery for air-conditioning applications in a mild climate: a case study

Indoor comfort requirements often involve strong ventilation in buildings, but they clash with the necessity to limit energetic and economic costs connected with supply air handling. The introduction of efficient thermal recovery from return air is therefore fundamental. In air-conditioning applications, also in the presence of the traditional solution which uses cooling coils for air dehumidification, it is possible to increase the reuse of return air thermohygrometric content if compared with simple sensible heat recovery between the two air streams. The opportunities connected with evaporative precooling of return air are analysed here in a frequent application case. The resulting advantages are superior to those ones offered by enthalpy recuperators.

Heat pump seasonal performance evaluation: a proposal for a European standard

A new simplified procedure to estimate seasonal performances of an air source heat pump is proposed here, based on a utilization factor method. This method permits one to evaluate heating energy requirement of buildings by a steady-state calculation with monthly average weather data, and it has been adopted by the European Community Technical Committee TC 89, as the basis of new energy standards. The results obtained by this procedure are compared with those by comprehensive computer programs such as DOE and BLAST.

Experimental analysis of a condenser heat recovery in an air conditioning plant

A total heat recovery system performances are analysed by monitoring building–plant system long term behaviour. Some of the installed chillers offer in fact the possibility of a total recovery of the heat rejected by condenser. The results are very satisfactory both in energy and economic–financial terms. The experimental test takes advantage of the supervisor just existing in the building. Therefore it is an example of how these control systems can be used not only for safety and management needs, but also for a detailed performance analysis able to permit an easy simulation of the effects of different design and control options.

Experimental study of ice storage performance in an office building

Effective reduction of electricity costs in conditioned buildings by using a cool storage installation is strictly dependent on optimal management and detailed prediction of the real operating conditions of the plant when designing the installation. Because of the multiplicity of causes which determine the final result, this is often very difficult to achieve. In this paper a monitoring test of a bank service central plant equipped with an ice storage cooling system is presented. The measured data show remarkable differences from design stage expectations. This confirms the necessity to always schedule a commissioning adjustment of this kind of system.

Energy roof as heat pump source/sink

Abstract An energy roof was considered both as a source for a heat pump and as a sink during the summer for a machine acting as an air conditioner. Performance looks very promising compared with similar systems which are equipped with finned coils utilizing the outside air as source/sink.

An analysis of next generation building energy simulation tools

SYNOPSIS Comprehensive software programs to simulate building energy performances in dynamic conditions are available today for professional purposes. In fact their modern releases are characterised by easy management and by the use of common personal computers. But, in spite of their better precision than simplified steady-state methods, many designers and even various standards, continue to prefer traditional simplified procedures. The possibilities and limits of new transient simulation software packages are investigated. This analysis starts from the results obtained, in some typical application cases, from the use of the two famous programs DOE and BLAST.

Parametric study on the financial performance of battery-supported photovoltaic systems connected to smart grids in current and future market scenarios

This article presents the economic performance of battery-supported residential photovoltaic systems connected to smart grids in the presence of a market-driven electricity tariff. In particular, the article deals with the economic benefit resulting on varied photovoltaic system and battery sizes, through a parametric analysis. Such an analysis is strongly dependent on the costs of photovoltaic systems and battery packs, which are prone to decrease in the coming years, according to many authors. In this context, the article investigates current and forecast economic scenarios, in order to show the expectable improvement in the financial performance in systems installed in the next few years. For this purpose, the article includes a review of photovoltaic system and battery prices forecasts for the coming years. The financial analysis takes into account two different (and conservative) feed-in tariffs: in the first case, the hourly national price of electricity is used as a feed in tariff, in the second case no reimbursement is considered for exported electricity, thus considering the case of wide photovoltaic system penetration and a consequent photovoltaic electricity overproduction.

Energy Optimization of a Building-plant System

A fundamental contribution to solve energy issues can come from the improvement of energy conversion efficiency and from the reduction of energy waste in buildings, as the energy consumption of such structures is a considerable quota of the total energy demand. The paper shows that the energy optimization of a building-plant system starts from a correct architectural and plant design. The opportunities offered by the introduction of high efficiency solutions are then presented by referring to experimental results of some building-plant systems in some structures in the Venetian area.

Building heating requirement calculation: a critical analysis of the new European standards

SYNOPSIS The simplified methods for the heating requirement calculation used in the new standard proposals are based on the utilisation factor for counting the dynamic effect of the building envelope. The proposed correlations give results only partially in agreement with detailed dynamic simulations. These differences are evident especially for the Southern European countries characterised by high solar radiation. Also high internal gains cause critical conditions for the standard applicability. The aim of this paper is to analyse some alternative equations for the utilisation factor in order to reduce these differences.